JP2016521052A - System and method for backward compatible preamble format for multiple access wireless communication - Google Patents

Abstract

Disclosed herein are systems, methods, and devices for wireless communication. One aspect of the present disclosure provides a method of receiving transmissions from two or more wireless communication devices. The method includes receiving a first preamble transmitted by a first wireless device, simultaneously receiving a second preamble transmitted by a second wireless device, and a first portion of the transmission. Receiving at a first section of bandwidth, wherein the first portion transmitted by the first wireless device includes a first data section; receiving the second portion of the transmission; Receiving simultaneously in the second section of width, wherein the second section of bandwidth does not overlap with the first section of bandwidth, and the second portion is transmitted by the second wireless device; The second portion includes receiving a second data section.

Description

  [0001] This application relates generally to wireless communications, and more particularly to systems, methods, and devices for enabling backward compatible multiple access wireless communications. As used herein, some aspects relate to orthogonal frequency division multiple access (OFDMA) communications, particularly in the IEEE 802.11 family of wireless communications standards.

  [0002] In many telecommunications systems, communication networks are used to exchange messages between several interacting spatially spaced devices. The network may be classified according to a geographical range, which may be, for example, a metropolitan area, a local area, or a personal area. Such networks may be designated as wide area networks (WAN), metropolitan area networks (MAN), local area networks (LAN), or personal area networks (PAN), respectively. The network also includes switching / routing techniques used to interconnect various network nodes and devices (eg, circuit switched vs. packet switched), the type of physical medium employed for transmission (eg, wired pair Wireless) and the set of communication protocols used (eg, Internet protocol suite, SONET (Synchronous Optical Networking), Ethernet, etc.).

  [0003] Wireless networks are often preferred when the network elements are mobile and thus have a need for dynamic connectivity, or when the network architecture is formed with an ad hoc topology rather than a fixed one. Wireless networks utilize intangible physical media in non-guided propagation modes that use electromagnetic waves in frequency bands such as radio, microwave, infrared, and light. Wireless networks advantageously facilitate user mobility and rapid field deployment compared to fixed wired networks.

  [0004] Each of the systems, methods, and devices of the present invention has several aspects, and none of the single aspects alone account for the desirable attributes of the present invention. Here, some features will be briefly described without limiting the scope of the present invention as represented by the following claims. In view of this discussion, particularly when reading the section entitled “Detailed Description”, those skilled in the art will understand how the features of the present invention provide advantages including efficient use of wireless media. .

  [0005] One aspect of the present disclosure provides a method of receiving transmissions from two or more wireless communication devices. The method includes receiving a first preamble transmitted by a first wireless device, simultaneously receiving a second preamble transmitted by a second wireless device, and a first portion of the transmission. Receiving at a first section of bandwidth, wherein the first portion transmitted by the first wireless device includes a first data section; receiving the second portion of the transmission; Receiving simultaneously in the second section of width, wherein the second section of bandwidth does not overlap with the first section of bandwidth, and the second portion is transmitted by the second wireless device; The second portion includes receiving a second data section.

  [0006] The first preamble may include a first section transmitted using a first format interpretable by a wireless device having a first capability set, and the wireless device having a second capability set A second section transmitted using a second format interpretable by the second preamble, wherein the second preamble uses the first format interpretable by a wireless device having a first capability set. May be included, and may further include a fourth section transmitted using a second format interpretable by a wireless device having a second capability. The first section of the first preamble and the third section of the second preamble are each a first type of training field used for automatic gain control, precise frequency offset estimation, time synchronization, And a second type of training field used for channel estimation and a signal field. The second section of the first preamble and the fourth section of the second preamble may each include one or more training fields of the second type. The amount of the second type of one or more training fields from a particular device may be based on the amount of spatial streams assigned to that particular wireless device. The amount of the second type of one or more training fields may be based on the amount of spatial streams assigned to the wireless device to which the most spatial streams are assigned. The first section of the first preamble may include a first training field of a first type, and the second section of the first preamble has a larger size than the first training field of the first type. A first type of second training field may be included, including a click shift. The first preamble may include a first type of training field, followed by a second type of one or more training fields, followed by a signal field, wherein the second preamble is a first type of training field. Type of training field, followed by a second type of one or more training fields, followed by a signal field, and immediately following data, the second in the second preamble The number of type training fields may be the same as the number of second type training fields of the first preamble. The first preamble may include a first type of training field, followed by a second type of one or more training fields, a subsequent signal field, and immediately following data. The first preamble may include a second type of one or more training fields, the second preamble may include a second type of one or more training fields, and in the first preamble The one or more training fields of the second type are in terms of time, in terms of frequency, or via code, for one or more training fields of the second type in the second preamble. And can be orthogonal. The first preamble may include one or more training fields of a second type, the transmission may include data sections sent on several spatial streams and several tones, One or more training fields of type are sent such that each of the spatial streams transmits known symbols over frequency tones that span both the first and second sections of bandwidth. The first preamble and the second preamble are each a signal field, followed by a first type of training field, followed by a second type of one or more training fields, followed by a first Two signal fields. Each of the first preamble and the second preamble each immediately follows a first type of training field, followed by a second type of one or more training fields, followed by a signal field. A first part and a second part of the transmission may be included. The first preamble may include symbols sent only within the first section of bandwidth, and the second preamble may include symbols sent only within the second section of bandwidth. The first section of bandwidth and the second section of bandwidth may each comprise a non-overlapping tone set.

  [0007] One aspect of the present disclosure provides an apparatus for wireless communication. The apparatus includes a receiver configured to receive transmissions over bandwidth. Receiving the transmission includes receiving a first preamble transmitted by the first wireless device, simultaneously receiving a second preamble transmitted by the second wireless device, and a first of the transmissions. Of the first portion of the bandwidth, wherein the first portion is transmitted by the first wireless device and includes a first data section; Of the second section of the bandwidth simultaneously, wherein the second section of the bandwidth does not overlap with the first section of the bandwidth, and the second section is received by the second wireless device Transmitted and the second portion includes receiving a second data section.

  [0008] The first preamble may include a first section transmitted using a first format interpretable by a wireless device having a first capability set, and the wireless device having a second capability set A second section transmitted using a second format interpretable by the second preamble, wherein the second preamble uses the first format interpretable by a wireless device having a first capability set. May be included, and may further include a fourth section transmitted using a second format interpretable by a wireless device having a second capability set.

  [0009] The first section of the first preamble and the third section of the second preamble are each a first type of training field used for automatic gain control and an accurate frequency offset estimate; A second type of training field used for time synchronization and channel estimation and a signal field may be included. The second section of the first preamble and the fourth section of the second preamble may each include one or more training fields of the second type. The amount of the second type of one or more training fields from a particular device may be based on the amount of spatial streams assigned to that particular wireless device. The amount of the second type of one or more training fields may be based on the amount of spatial streams assigned to the wireless device to which the most spatial streams are assigned.

  [0010] One aspect of the present disclosure provides an apparatus for wireless communication. The apparatus includes: means for receiving a first preamble transmitted by a first wireless device; means for simultaneously receiving a second preamble transmitted by a second wireless device; Means for receiving a first portion at a first section of bandwidth, wherein the first portion transmitted by the first wireless device includes a first data section; and Means for simultaneously receiving a second portion of transmission in a second section of bandwidth, wherein the second section of bandwidth does not overlap with the first section of bandwidth; The portion is transmitted by a second wireless device, and the second portion includes means for receiving, including a second data section.

FIG. 3 shows channel allocation for available channels for an IEEE 802.11 system. The figure which shows the structure of the physical layer packet (PPDU frame) which may be used in IEEE802.11a / b / g / j / p communication. The figure which shows the structure of the physical layer packet (PPDU frame) which may be used in IEEE802.11n communication. The figure which shows the structure of the physical layer packet (PPDU frame) which can be used in IEEE802.11ac communication. FIG. 3 illustrates an example structure of a downlink physical layer packet that can be used to enable backward compatible multiple access wireless communications. FIG. 4 is an exemplary diagram of signals that can be used to identify STAs and assign subbands to those STAs. FIG. 4 illustrates a second example structure of a downlink physical layer packet that may be used to enable backward compatible multiple access wireless communications. FIG. 4 illustrates a third example structure of a downlink physical layer packet that may be used to enable backward compatible multiple access wireless communications. FIG. 4 illustrates a fourth example structure of a downlink physical layer packet that may be used to enable backward compatible multiple access wireless communications. 1 is a diagram illustrating an example of a wireless communication system in which aspects of the present disclosure may be employed. FIG. 2 is a functional block diagram of an exemplary wireless device that may be employed within the wireless communication system of FIG. FIG. 4 illustrates an example structure of an uplink physical layer packet that can be used to enable backward compatible multiple access wireless communications. FIG. 5 is a process flow diagram for an example method for transmitting high efficiency packets to two or more wireless communication devices. FIG. 4 illustrates an example structure of a hybrid downlink physical layer packet that can be used to enable backward compatible multiple access wireless communications. FIG. 3 shows an exemplary method for transmitting a hybrid packet. FIG. 3 illustrates an example method for receiving a hybrid packet. FIG. 4 shows a packet having one exemplary HE preamble format. FIG. 5 shows a packet with another exemplary HE preamble format. FIG. 5 shows a packet with another exemplary HE preamble format. FIG. 6 shows an exemplary bit allocation for the HE-SIG1 field. FIG. 4 illustrates an example structure of an uplink physical layer packet that can be used to enable backward compatible multiple access wireless communications. FIG. 4 illustrates another example structure of an uplink physical layer packet that may be used to enable backward compatible multiple access wireless communications. FIG. 3 shows an exemplary method for receiving a packet. FIG. 4 illustrates an example uplink packet structure for uplink HE packets. FIG. 4 illustrates an example uplink packet structure for uplink HE packets. FIG. 4 illustrates an example downlink message from an AP that includes information regarding how many spatial streams each transmitting device may use. FIG. 4 shows a tone interleaving LTF that may be used in a UL OFDMA packet. FIG. 4 shows a subband interleaved LTF that may be used in a UL OFDMA packet. FIG. 3 illustrates an example LTF portion of a packet that may be transmitted in a UL OFDMA packet. FIG. 6 shows a packet with a common SIG field prior to HE-STF and a per-user SIG field after all HE-LTFs. FIG. 4 illustrates an example method of transmitting to one or more devices in a single transmission. FIG. 4 illustrates an example method of transmitting to one or more first devices having a first capability set and transmitting simultaneously to one or more second devices having a second capability set. FIG. 4 illustrates an example method for receiving a transmission that is compatible with both a device having a first capability set and a device having a second capability set. FIG. 6 illustrates an example method of receiving a transmission in which portions of the transmission are transmitted by different wireless devices. FIG. 7 is an illustration of various components that may be utilized in a wireless device that may be employed within a wireless communication system.

Detailed description

  Various aspects of the novel system, apparatus, and method are described more fully hereinafter with reference to the accompanying drawings. However, the disclosed teachings can be implemented in many different forms and should not be construed as limited to any particular structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein, one of ordinary skill in the art will implement independent of any other aspect of the invention or in combination with any other aspect of the invention. Regardless, it should be appreciated that the scope of the present disclosure is intended to encompass any aspect of the novel systems, devices, and methods disclosed herein. For example, an apparatus can be implemented or a method can be implemented using any number of aspects described herein. In addition, the scope of the present invention is such that it is implemented using other structures, functions, or structures and functions in addition to or other than the various aspects of the present invention described herein. It is intended to encompass an apparatus or method. It should be understood that any aspect disclosed herein may be implemented by one or more elements of a claim.

  Although particular aspects are described herein, many variations and permutations of these aspects fall within the scope of the disclosure. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the disclosure is not intended to be limited to particular advantages, uses, or objectives. Rather, aspects of the present disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks, and transmission protocols, some of which are illustrated by way of example in the drawings and the following description of preferred embodiments. Indicated. The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims and equivalents thereof.

  Wireless network technology may include various types of wireless local area networks (WLANs). WLANs can be used to interconnect neighboring devices together that employ widely used networking protocols. Various aspects described herein may apply to any communication standard, such as WiFi®, or more generally, any member of the IEEE 802.11 family of wireless protocols. For example, various aspects described herein may be used as part of an IEEE 802.11 protocol, such as the 802.11 protocol that supports orthogonal frequency division multiple access (OFDMA) communications.

  It may be beneficial to allow multiple devices, such as STAs, to communicate with the AP at the same time. For example, this may allow multiple STAs to receive a response from the AP in a shorter time and to send and receive data from the AP with a shorter delay. This may also allow the AP to communicate with a greater number of devices overall, and may make bandwidth usage more efficient. By using multiple access communication, the AP may be able to multiplex OFDM symbols, for example, to four devices at a time via an 80 MHz bandwidth, where each device has a 20 MHz bandwidth. Is used. Thus, multiple access may be beneficial in some variations because multiple access may allow an AP to use the spectrum available to that AP more efficiently.

  Proposed to implement such a multiple access protocol in an OFDM system, such as 802.11 family, by assigning different subcarriers (or tones) of symbols transmitted between AP and STA to different STAs Has been. In this way, an AP can communicate with multiple STAs using a single transmitted OFDM symbol, where different tones of the symbol are encoded and processed by different STAs, and thus multiple Allows simultaneous data transfer to the STA. These systems are sometimes referred to as OFDMA systems.

  Such tone allocation schemes are referred to herein as “high efficiency” (HE) systems, and data packets transmitted within such multiple tone allocation systems may be referred to as high efficiency (HE) packets. . Various structures of such packets including a backward compatible preamble field are described in detail below.

  Various aspects of the novel system, apparatus, and method are described more fully hereinafter with reference to the accompanying drawings. However, this disclosure may be implemented in many different forms and should not be construed as limited to any particular structure or function shown throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein, one of ordinary skill in the art will implement independent of any other aspect of the invention or in combination with any other aspect of the invention. Regardless, it should be appreciated that the scope of the present disclosure is intended to encompass any aspect of the novel systems, devices, and methods disclosed herein. For example, an apparatus can be implemented or a method can be implemented using any number of aspects described herein. In addition, the scope of the present invention is such that it is implemented using other structures, functions, or structures and functions in addition to or other than the various aspects of the present invention described herein. It is intended to encompass an apparatus or method. It should be understood that any aspect disclosed herein may be implemented by one or more elements of a claim.

  Although particular aspects are described herein, many variations and permutations of these aspects fall within the scope of the disclosure. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the disclosure is not intended to be limited to particular advantages, uses, or objectives. Rather, aspects of the present disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks, and transmission protocols, some of which are illustrated by way of example in the drawings and the following description of preferred embodiments. Indicated. The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims and equivalents thereof.

  Popular wireless network technologies may include various types of wireless local area networks (WLANs). WLANs can be used to interconnect neighboring devices together that employ widely used networking protocols. Various aspects described herein may be applied to any communication standard such as a wireless protocol.

  In some aspects, the wireless signal may be transmitted according to the 802.11 protocol. In some implementations, the WLAN includes various devices that are components that access the wireless network. For example, there may be two types of devices: an access point (AP) and a client (also referred to as a station or STA). In general, an AP can function as a hub or base station for a WLAN, and a STA functions as a WLAN user. For example, the STA can be a laptop computer, a personal digital assistant (PDA), a mobile phone, and the like. In one example, the STA connects to the AP via a WiFi compatible wireless link for general connectivity to the Internet or other wide area network. In some implementations, the STA may also be used as an AP.

  An access point (AP) may also comprise, be implemented as, or be referred to as a base station, a wireless access point, an access node, or similar terminology.

  Station “STA” comprises an access terminal (AT), subscriber station, subscriber unit, mobile station, remote station, remote terminal, user terminal, user agent, user device, user equipment, or other terms, as Sometimes implemented or referred to by these terms. Accordingly, one or more aspects taught herein include a telephone (eg, a cellular phone or a smartphone), a computer (eg, a laptop), a portable communication device, a headset, a portable computing device (eg, portable information Terminal), entertainment device (eg, music device or video device, or satellite radio), gaming device or gaming system, global positioning system device, or any other suitable configured for network communication via wireless media May be built into other devices.

  As discussed above, some of the devices described herein may implement, for example, the 802.11 standard. Such a device can be used for smart meter reading or in a smart grid network, whether it is used as a STA, used as an AP, or used as another device. Such devices can provide sensor applications or be used in home automation. The device can alternatively or additionally be used in a health care setting, for example for personal health care. They can also be used for monitoring to allow a wide range of Internet connections (eg, for use with hotspots) or to implement machine-to-machine communication.

  FIG. 1 shows the channel allocation for channels available for the IEEE 802.11 system. Various IEEE 802.11 systems support several different sized channels, such as 5 MHz channel, 10 MHz channel, 20 MHz channel, 40 MHz channel, 80 MHz channel, and 160 MHz channel. For example, an 802.11ac device may support 20 MHz, 40 MHz, and 80 MHz channel bandwidth reception and transmission. A larger channel may comprise two adjacent smaller channels. For example, an 80 MHz channel may comprise two adjacent 40 MHz channels. In the currently implemented IEEE 802.11 system, a 20 MHz channel includes 64 subcarriers separated from each other by 312.5 kHz. Among these subcarriers, a smaller number of subcarriers can be used to carry data. For example, a 20 MHz channel may include transmit subcarriers numbered from −1 subcarrier to −28 subcarrier and 1 subcarrier to 28 subcarrier, or 56 subcarriers. Some of these carriers can also be used to transmit pilot signals. Over the years, the IEEE 802.11 standard has evolved through several versions. Older versions include the 11a / g version and the 11n version. The most recent release is the 802.11ac version.

  2, 3 and 4 show data packet formats for some existing IEEE 802.11 standards. Referring first to FIG. 2, the packet formats for IEEE 802.11a, 11b, and 11g are shown. This frame includes a short training field 22, a long training field 24, and a signal field 26. The training field does not transmit data, but the training field allows synchronization between the AP and the receiving STA to decode the data in the data field 28.

  The signal field 26 delivers information about the nature of the packet being delivered from the AP to the STA. In IEEE 802.11a / b / g devices, this signal field has a length of 24 bits and uses BPSK modulation and 1/2 code rate as a single OFDM symbol at a rate of 6 Mb / s. Sent. The information in the SIG field 26 includes 4 bits that describe the modulation scheme (eg, BPSK, 16QAM, 64QAM, etc.) of the data in the packet and 12 bits related to the packet length. This information is used by the STA to decode the data in the packet when the packet is targeted to the STA. When a packet is not intended for a particular STA, the STA will postpone any communication attempt for the time period defined in the length field of the SIG symbol 26, and to save power, Sleep mode can be entered for a packet period of approximately 5.5 milliseconds.

  As features were added to IEEE 802.11, changes to the format of the SIG field in the data packet were developed to provide additional information to the STA. FIG. 3 shows the packet structure for an IEEE 802.11n packet. The addition of 11n to the IEEE 802.11 standard added a MIMO function to the IEEE 802.11 compatible device. In order to provide backward compatibility for systems that include both IEEE 802.11a / b / g and IEEE 802.11n devices, data packets for IEEE 802.11n systems should also indicate that they are “legacy” fields. It includes the earlier STF field, LTF field, and SIG field of these systems, known as L-STF 22, L-LTF 24, and L-SIG 26, with a prefix L to indicate. Two additional signal symbols 140 and 142 were added to the IEEE 802.11n data packet to provide the STA with the information needed in the IEEE 802.11n environment. However, in contrast to the SIG field and the L-SIG field 26, these signal fields used rotational BPSK modulation (also called QBPSK modulation). When a legacy device configured to operate with IEEE 802.11a / b / g receives such a packet, the legacy device receives the L-SIG field 26 as a normal 11a / b / g packet and It will be decrypted. However, the format of the data packet after the L-SIG field 26 is different from the format of the 11a / b / g packet, so that if the device continues to decode additional bits, those bits will not be successfully decoded. The CRC check performed by the device during this process will fail. This causes these legacy devices to stop processing the packet, but also delays further operation until the time period defined by the length field in the originally decoded L-SIG has elapsed. In contrast, a new device that is compatible with IEEE 802.11n will sense the rotational modulation in the HT-SIG field and process the packet as an 802.11n packet. Furthermore, if the 11n device senses any modulation other than QBPSK in the symbol following L-SIG 26, the 11n device will ignore it as an 11a / b / g packet, so the 11n device will receive the packet as 11a / b. / G Device can be identified. After the HT-SIG1 and SIG2 symbols, an additional training field suitable for MIMO communication is provided, followed by data 28.

  FIG. 4 shows a frame format for the existing IEEE 802.11ac standard in which a multi-user MIMO function is added to the IEEE 802.11 family. Similar to IEEE 802.11n, an 802.11ac frame includes the same legacy short training field (L-STF) 22 and long training field (L-LTF) 24. The 802.11ac frame also includes the legacy signal field L-SIG 26 described above.

  Next, the 802.11ac frame includes two symbol lengths of the very high throughput signal (VHT-SIG-A1 150 and A2 152) fields. This signal field provides additional configuration information regarding 11ac features that are not present in 11a / b / g and 11n devices. The first OFDM symbol 150 of the VHT-SIG-A may be modulated using BPSK so that any 802.11n device listening to the packet is confident that the packet is an 802.11a packet Will postpone the packet for the duration of the packet length defined in the length field of the L-SIG 126. Devices configured according to 11a / g will expect a service field and a MAC header following the L-SIG26 field. When these devices attempt this decoding, a CRC failure will occur in a manner similar to the procedure when 11n packets are received by the 11a / b / g device, and the 11a / b / g device Will also be postponed for the period defined in the L-SIG field 26. The second symbol 152 of VHT-SIG-A is modulated with 90 degree rotated BPSK. This rotated second symbol enables the 80211ac device to identify the packet as an 802.11ac packet. VHT-SIGA1 150 field and A2 152 field contain information on bandwidth mode, information on modulation and coding scheme (MCS) for single user, information on number of space time streams (NSTS), and other information . VHT-SIGA1 150 and A2 152 may also include a number of reserved bits set to “1”. The legacy field and the VHT-SIGA1 field and the A2 field can be duplicated through each 20 MHz of available bandwidth.

  After VHT-SIG-A, the 802.11ac packet may include a VHT-STF configured to improve automatic gain control estimation in multiple-input multiple-output (MIMO) transmission. The next 1 to 8 fields of the 802.11ac packet may be VHT-LTF. These can be used to estimate the MIMO channel and then equalize the received signal. The number of VHT-LTFs sent may be greater than or equal to the number of spatial streams per user. Finally, the last field in the preamble before the data field is VHT-SIG-B 154. This field is BPSK modulated and provides information about the length of useful data in the packet, and in the case of multi-user (MU) MIMO packets, provides MCS. In the case of a single user (SU), this MCS information is instead included in VHT-SIGA2. Subsequent to VHT-SIG-B, data symbols are transmitted. 802.11ac introduces various new features into the 802.11 family, includes data packets with a preamble design that is backward compatible with 11a / g / n devices, and is necessary to implement the new features of 11ac However, configuration information regarding OFDMA tone allocation for multiple access is not provided by the 11ac data packet design. In order to implement such features in any future version of IEEE 802.11, or any other wireless network protocol that uses OFDM subcarriers, a new preamble configuration is required. In the following, an advantageous preamble design is presented in particular with reference to FIGS.

  FIG. 5 illustrates an example structure of physical layer packets that may be used to enable backward compatible multiple access wireless communication in this environment.

  This exemplary physical layer packet includes a legacy preamble that includes an L-STF 22, an L-LTF 26, and an L-SIG 26. Each of these may be transmitted using 20 MHz, and multiple copies may be transmitted for each 20 MHz spectrum used by the AP.

  The packet also includes a HE-SIG1 symbol 455, a HE-SIG2 symbol 457, and one or more HE-SIG3 symbols 459. The structure of these symbols should be backward compatible with the IEEE 802.11a / b / g / n / ac device and should signal to the OFDMA HE device that the packet is a HE packet. In order to be backward compatible with IEEE 802.11a / b / g / n / ac devices, appropriate modulation may be used for each of these symbols. In some implementations, the first symbol HE-SIG1 455 may be modulated with BPSK modulation. This has the same effect on 11a / b / g / n devices as the current case with 11ac packets that also modulated their first SIG symbol BPSK. For these devices, it does not matter what modulation is performed on the subsequent HE-SIG symbols 457, 459. Second symbol 457 may be BPSK modulated or QPSK modulated. When BPSK modulated, the 11ac device will consider the packet to be an 11a / b / g packet and will stop processing that packet for the time defined by the length field of the L-SIG 26. Will be postponed. If QBPSK modulated, the 11ac device will generate a CRC error during preamble processing and will also stop processing that packet, for the time defined by the length field of the L-SIG, Will be postponed. To signal to the HE device that this is a HE packet, at least a first symbol of HE-SIG3 459 may be QBPSK modulated.

  The information necessary to establish OFDMA multiple access communication may be located at various locations within HE-SIG fields 455, 457, and 459. In the example of FIG. 5, HE-SIG1 455 includes tone allocation information for OFDMA operation. HE-SIG3 459 includes bits defining a user specific modulation type for each multiplexed user. In addition, HE-SIG2 457 includes bits defining a user specific MIMO spatial stream as provided in the 11ac format of FIG. The example of FIG. 5 may allow each of four different users to be assigned a specific subband of tones and a specific number of MIMO space time streams. The 12-bit spatio-temporal stream information allows 3 bits for each of the 4 users so that 1-8 streams can be assigned to each. 16-bit modulation type data allows 4 bits for each of the 4 users and allows any one of 16 different modulation schemes (16QAM, 64QAM, etc.) to be assigned to each of the 4 users To do. The 12-bit tone allocation data allows a particular subband to be assigned to each of the four users.

  One exemplary SIG field scheme for subband allocation is shown in FIG. This example includes a 6-bit group ID field similar to that currently used in IEEE 802.11ac, as well as 10-bit information for allocating subband tones to each of four users. The bandwidth used to deliver the packet 130 may be allocated to the STA in some number of multiples of MHz. For example, bandwidth can be allocated to STAs in multiples of B MHz. The value of B can be a value such as 1 MHz, 2 MHz, 5 MHz, 10 MHz, 15 MHz, or 20 MHz. The value of B can be provided by the 2-bit allocation granularity field of FIG. For example, HE-SIG 155 may include one 2-bit field that allows four possible values of B. For example, the value of B can be 5 MHz, 10 MHz, 15 MHz, or 20 MHz, corresponding to values of 0-3 in the allocation granularity field. In some aspects, a k-bit field may be used to signal a B value that defines a number from 0 to N, where 0 is the least flexible option (maximum A high value of N represents the most flexible option (the minimum granularity). Each B MHz portion may be referred to as a subband.

  HE-SIG1 can further use 2 bits per user to indicate the number of subbands allocated to each STA. This may allow 0-3 subbands to be allocated to each user. The group id (G_ID) concept from 802.11ac may be used to identify the STAs that will receive data in the OFDMA packet. This 6-bit G_ID can identify up to four STAs in a particular order in this example.

  In this example, the allocation granularity field is set to “00”. In this example, the allocation granularity field is a 2-bit field, and its value may correspond to 5 MHz, 10 MHz, 15 MHz, or 20 MHz in order. For example, “00” may correspond to an allocation granularity of 5 MHz.

  In this example, the first two bits give the number of subbands for the first user identified by G_ID. Here, the subband “11” is given to the user 1. This may correspond to user 1 receiving three subbands. If each subband is 5 MHz, this may mean that User 1 is allocated a 15 MHz spectrum. Similarly, user 2 still receives 3 subbands, whereas user 3 receives zero subbands and user 4 receives 2 subbands. Thus, this allocation may correspond to a 40 MHz signal where 15 MHz is used for both user 1 and user 2 whereas user 4 receives 10 MHz and user 3 receives no subbands.

  Training fields and data sent after the HE-SIG symbol are delivered by the AP to each STA according to the assigned tone. This information can potentially be beamformed. Beamforming this information may have several advantages, such as allowing more accurate decoding and / or providing a greater range than non-beamformed transmissions.

  Depending on the space time stream assigned to each user, different users may require a different number of HE-LTFs 165. Each STA may generally require a number of HE-LTFs 165 that allow channel estimation for each spatial stream associated with the STA equal to or greater than the number of spatial streams. LTF can also be used for frequency offset estimation and time synchronization. Since different STAs may receive different numbers of HE-LTFs, symbols that include HE-LTF information on one tone and data on other tones may be transmitted from the AP.

  In some aspects, sending both HE-LTF information and data on the same OFDM symbol may be problematic. For example, this can increase the peak-to-average power ratio (PAPR) to a too high level. Thus, instead, it may be beneficial to transmit HE-LTF 165 on all tones of the transmitted symbol until each STA receives at least the required number of HE-LTFs 165. For example, each STA may need to receive one HE-LTF 165 per spatial stream associated with the STA. Thus, the AP may be configured to send a number of HE-LTFs 165 equal to the maximum number of spatial streams assigned to any STA to each STA. For example, if a single spatial stream is assigned to three STAs, but a third spatial stream is assigned to the fourth STA, in this aspect, before the AP transmits a symbol containing payload data, Four symbols of HE-LTF information may be configured to be transmitted to each of the four STAs.

  The tones assigned to any given STA need not be adjacent. For example, in some implementations, subbands of different receiving STAs may be interleaved. For example, if user 1 and user 2 each receive three subbands while user 4 receives two subbands, these subbands may be interleaved across the entire AP bandwidth. For example, these subbands may be interleaved in the order 1, 2, 4, 1, 2, 4, 1, 2, etc. In some aspects, other methods for interleaving subbands may also be used. In some aspects, interleaving subbands may reduce the adverse effects of interference or the effects of poor reception from a particular device on a particular subband. In some aspects, the AP may transmit to the STA on a subband that the STA prefers. For example, certain STAs may have better reception within some subbands than other subbands. Thus, the AP can transmit to the STA based at least in part on which subband the STA may have better reception. In some aspects, the subbands may also not be interleaved. For example, the subbands may instead be transmitted as 1,1,1,2,2,2,4,4. In some aspects, whether subbands are interleaved may be predefined.

  In the example of FIG. 5, HE-SIG3 symbol modulation may be used to signal to the HE device that the packet is a HE packet. Other methods of signaling to the HE device that the packet is a HE packet may be used. In the example of FIG. 7, the L-SIG 126 may include information indicating to the HE device that the HE preamble will follow the legacy preamble. For example, the L-SIG 26 may include a low energy 1-bit code on the Q rail that indicates the presence of a subsequent HE preamble to HE devices that are sensitive to the Q signal during the L-SIG 26. Since a single bit signal can be spread across all tones used by the AP to transmit a packet, a Q signal with very low amplitude can be used. This code can be used by a high efficiency device to detect the presence of the HE preamble / packet. The L-SIG26 detection sensitivity of legacy devices is not necessarily substantially affected by this low energy code on the Q rail. Thus, these devices will be able to read the L-SIG 26 and will not be aware of the presence of the code, whereas the HE device can detect the presence of the code. In this implementation, if desired, all HE-SIG fields can be BPSK modulated, and any of the techniques described herein for legacy compatibility can be used with this L-SIG signaling.

  FIG. 8 shows another way to implement backward compatibility with 11ac devices as well. In this example, HE-SIG-A1 455 may include bits set to a value that is flipped from the value required by the 11ac device when decoding the VHT-SIG field. For example, the 802.11ac VHT-SIG-A field includes bits 2 and 23 that are reserved and set to 1 in the correctly assembled VHT-SIG-A field. In the high efficiency preamble HE-SIG-A455, one or both of these bits may be set to zero. If an 802.11ac device receives a packet containing a reserved bit with such a flipped value, the 11ac device stops processing the packet and is specified in the L-SIG 26 Treat the packet as undecodable while still postponing the packet for the duration. In this implementation, backward compatibility with 11a / b / g / n devices may be achieved by using BPSK modulation for HE-SIG1 symbols 455, and signaling to HE devices may be HE-SIG2 457 or This may be achieved by using QBPSK modulation for one or more symbols of HE-SIG3 459.

  As shown by the example shown in FIG. 9, the structure of the HE packet can be based on the packet structure used in 802.11ac. In this example, after the legacy preambles 22, 24, 26, two symbols, referred to as HE-SIGA1 and HE-SIGA2 in FIG. 9, are provided. This is the same structure as VHT-SIGA1 and VHT-SIGA2 in FIG. In order to adapt both space-time stream allocation and tone allocation to these two 24-bit symbols, less freedom is given to the space-time stream option.

  The example of FIG. 9 also places a HE-SIGB symbol 459 after the HE training field, similar to the VHT-SIGB field 154 of FIG.

However, one potential problem with this 11ac-based preamble is that this design can fall into the HE-SIG-B470 space limitation. For example, HE-SIG-B 470 may need to include at least MCS (4 bits) and tail bits (6 bits). Accordingly, HE-SIG-B 470 may need to contain at least 10 bits of information. In the 802.11ac specification, VHT-SIG-B is one OFDM symbol. However, depending on the bandwidth of each subband, there may not be a sufficient number of bits in a single OFDM symbol. For example, Table 1 below illustrates this potential problem.

  As shown in Table 1, if each subband is 10 MHz, a single OFDM symbol provides 13 bits. Six of these bits are required as tail bits, so 7 bits remain for the MCS field. As mentioned above, the MCS field requires 4 bits. Thus, if each subband is at least 10 MHz, a single OFDM symbol may be used for HE-SIG-B 470, which may be sufficient to include a 4-bit MCS field. However, if each subband is instead 5 MHz or 6 MHz, this may only allow 6 or 8 bits per OFDM symbol. Of these bits, 6 bits are tail bits. Therefore, only 0 or 2 bits are available for the MCS field. This is insufficient to provide an MCS field. In these cases where the subband granularity is too small to provide the information needed in the SIGB field, more than one OFDM symbol may be used for HE-SIG-B470. The number of symbols required is related to the smallest subband that the system allows. If this is 5 MHz, corresponding to 13 tones in an IEEE 802.11 family OFDM system, the two symbols for HE-SIG-B are long enough for the HE-SIG-B information MCS and tail bits. To provide BPSK modulation and 1/2 forward error correction code rate to provide 12 bits. FIG. 10 illustrates an example of a wireless communication system 100 in which aspects of the present disclosure may be employed. The wireless communication system 100 can operate in accordance with a wireless standard, such as the IEEE 802.11 standard. The wireless communication system 100 may include an AP 104 that communicates with STAs 106a, 106b, 106c, and 106d (collectively STAs 106). The network may include both legacy STAs 106b and high efficiency (HE) STAs 106a, 106c, 106d.

  Various processes and methods may be used for transmission in the wireless communication system 100 between the AP 104 and the STA 106. For example, signals can be transmitted and received between the AP 104 and the STA 106 according to OFDM / OFDMA techniques. If this is the case, the wireless communication system 100 may be referred to as an OFDM / OFDMA system.

  A communication link that facilitates transmission from the AP 104 to one or more of the STAs 106 may be referred to as a downlink (DL) 108 and facilitates transmission from one or more of the STAs 106 to the AP 104. The communication link may be referred to as the uplink (UL) 110. Alternatively, downlink 108 may be referred to as the forward link or forward channel, and uplink 110 may be referred to as the reverse link or reverse channel. In some aspects, some DL 108 communications may be HE packets, such as HE packet 130. Such HE packets contain sufficient information to cause legacy STA 106b to recognize HE packet 130 and defer transmission of HE packet 130 for the duration of its transmission, such as 802.11a and 802.11n, etc. Legacy preamble information such as preamble information according to Similarly, the DL 108 communication, which is the HE packet 130, provides sufficient information to inform the HE STAs 160a, 106c, 106d which devices can receive information in the HE packet 130, as discussed above. May be included.

  The AP 104 may act as a base station and provide wireless communication coverage within the basic service area (BSA) 102. An AP 104 may be referred to as a basic service set (BSS), along with a STA 106 that is associated with the AP 104 and uses the AP 104 for communication. It should be noted that the wireless communication system 100 may not have a central AP 104, but rather may function as a peer-to-peer network between the STAs 106. Accordingly, the functions of the AP 104 described herein may alternatively be performed by one or more of the STAs 106.

  FIG. 11 is a diagram illustrating various components that may be utilized by a wireless device 202 that may be employed within the wireless communication system 100. Wireless device 202 is an example of a device that may be configured to implement the various methods described herein. For example, the wireless device 202 may comprise one of the AP 104 of FIG. In some aspects, the wireless device 202 may comprise an AP configured to transmit HE packets, such as the HE packet 130.

  The wireless device 202 may include a processor 204 that controls the operation of the wireless device 202. The processor 204 may also be referred to as a central processing unit (CPU). Memory 206, which may include both read only memory (ROM) and random access memory (RAM), provides instructions and data to processor 204. A portion of memory 206 may also include non-volatile random access memory (NVRAM). The processor 204 typically performs logical and arithmetic operations based on program instructions stored in the memory 206. The instructions in memory 206 may be executable to implement the methods described herein. For example, if the wireless device 202 is an AP 104, the memory 206 may include sufficient instructions to allow the wireless device 202 to transmit HE packets, such as the HE packet 130. For example, the memory 206 may include sufficient instructions to allow the wireless device 202 to transmit a legacy preamble followed by a HE preamble that includes HE-SIG or HE-SIG-A. In some aspects, the wireless device 202 may include a frame format circuit 221 that may include sufficient instructions to allow the wireless device 202 to transmit frames in accordance with the embodiments disclosed herein. For example, the frame format circuit 221 may include sufficient instructions to allow the wireless device 202 to transmit a packet that includes both a legacy preamble and a high efficiency preamble.

  The processor 204 may comprise or be a component of a processing system implemented with one or more processors. The one or more processors include a general purpose microprocessor, microcontroller, digital signal processor (DSP), field programmable gate array (FPGA), programmable logic device (PLD), controller, state machine, gated logic, discrete hardware It may be implemented with any combination of components, dedicated hardware finite state machines, or any other suitable entity capable of performing information calculations or other operations.

  The processing system may also include a machine readable medium for storing software. Software shall be interpreted broadly to mean any type of instruction, whether referred to as software, firmware, middleware, microcode, hardware description language, or other terminology. . The instructions may include code (eg, in source code format, binary code format, executable code format, or any other suitable code format). The instructions, when executed by one or more processors, cause the processing system to perform various functions described herein.

  The wireless device 202 may also include a housing 208 that may include a transmitter 210 and a receiver 212 that allow transmission and reception of data between the wireless device 202 and a remote location. Transmitter 210 and receiver 212 may be coupled to transceiver 214. Antenna 216 may be attached to housing 208 and electrically coupled to transceiver 214. The wireless device 202 may also include multiple transmitters, multiple receivers, multiple transceivers, and / or multiple antennas (not shown).

  The wireless device 202 may also include a signal detector 218 that may be used to detect and quantify the level of the signal received by the transceiver 214. The signal detector 218 can detect signals such as total energy, energy per subcarrier per symbol, power spectral density, and other signals. The wireless device 202 may also include a digital signal processor (DSP) 220 for use in processing signals. The DSP 220 may be configured to generate a data unit for transmission. In some aspects, the data unit may comprise a physical layer data unit (PPDU). In some aspects, the PPDU is referred to as a packet.

  In some aspects, the wireless device 202 may further comprise a user interface 222. User interface 222 may include a keypad, microphone, speaker, and / or display. User interface 222 may include any element or component that conveys information to a user of wireless device 202 and / or receives input from the user.

  Various components of the wireless device 202 may be coupled together by a bus system 226. Bus system 226 may include, for example, a data bus, as well as a data bus, a power bus, a control signal bus, and a status signal bus. Those skilled in the art will appreciate that the components of the wireless device 202 can be coupled together using any other mechanism or can accept or provide input to each other.

  Although several separate components are shown in FIG. 11, one or more of these components can be combined or implemented in common. For example, the processor 204 can be used not only to implement the functions described above with respect to the processor 204, but also to implement the functions described above in connection with the signal detector 218 and / or the DSP 220. In addition, each of the components shown in FIG. 11 can be implemented using a plurality of separate elements. Further, processor 204 can be used to implement any of the components, modules, circuits, etc. described below, or each can be implemented using a plurality of separate elements.

  FIG. 12 shows an exemplary structure of an uplink physical layer packet 830 that can be used to enable backward compatible multiple access wireless communications. In such an uplink message, the legacy preamble is not required because the NAV is set by the AP's first downlink message. Accordingly, the uplink packet 830 does not include a legacy preamble. Uplink packet 830 may be sent in response to a UL-OFDMA announcement message sent by the AP.

  Uplink packet 830 may be sent by several different STAs. For example, each STA identified in the downlink packet may transmit a portion of the uplink packet 830. Each of the STAs can transmit simultaneously within its allocated bandwidth or within multiple bandwidths, and the transmission can be received by the AP as a single packet.

  In packet 830, each STA uses only the channel or subband assigned to that STA during tone assignment in the initial downlink message, as described above. This allows complete orthogonal reception processing on the AP. In order to receive messages on each of these subbands, the AP must receive a pilot tone. These pilot tones are used in the 802.11 packet for phase tracking to estimate the phase offset per symbol to correct for phase changes across data symbols due to residual frequency offset or due to phase noise Is done. This phase offset can also be sent to a time and frequency tracking loop.

  At least two different options may be used to transmit pilot tones. First, each user can transmit a pilot tone corresponding to its assigned subband. However, for low bandwidth OFDMA allocation, this may not allow a sufficient number of pilot tones for some users. For example, there are four pilot tones for a 20 MHz transmission in 802.11a / n / ac. However, if a user is assigned only 5 MHz, that user may have only one pilot tone in that subband. If some problem occurs with that pilot tone, such as deep fade, it can be very difficult to obtain a good phase estimate.

  Another possible way of transmitting pilot tones may be related to each user transmitting on all pilot tones, not just the pilot tones applicable to that subband. This can result in having multiple pilot tones transmitted per user. However, this can result in the AP receiving each pilot tone from multiple users simultaneously, which can be more difficult for the AP to process. The AP will need to estimate the channel for all users. To achieve this, more LTFs may be required, such as a number corresponding to the sum of all users' spatial streams. For example, if each of four users is associated with two spatial streams, this approach may use eight LTFs.

  In this way, each STA can transmit HE-STF 835. As shown in packet 830, HE-STF 835 may be transmitted in 8us and may include two OFDMA symbols. Each STA may also transmit one or more HE-LTFs 840. As shown in packet 830, HE-LTF 840 may be transmitted in 8us and may include two OFDMA symbols. For example, as described above, each STA can transmit a HE-LTF 840 for each subband assigned to that STA. Each STA can also transmit HE-SIG 845. The length of HE-SIG 845 may be one ODFMA symbol length (4 us) for each of U, where U is the number of STAs multiplexed in transmission. For example, if 4 STAs are sending uplink packets 830, HE-SIG 845 may be 16us. After HE-SIG 845, an additional HE-LTF 840 may be transmitted. Finally, each STA can transmit data 855.

  In order to send the combined uplink packet 830, each of the STAs can synchronize with each other in terms of time, frequency, and power with the other STAs. The timing synchronization required for such a packet can be on the order of about 100 ns. This timing may be coordinated by responding to the AP's UL-OFDMA announcement message. This timing accuracy can be obtained using several solutions known to those skilled in the art. For example, the technique used by 802.11ac and 802.11n devices to time short interframe space (SIFS) provides the timing accuracy needed to obtain a combined uplink packet 830. It may be enough to do. This timing accuracy is also maintained by using a guard interval of 800 ns length only for uplink OFDMA to obtain 400 ns guard time in order to absorb timing errors and round trip delay differences between uplink clients. Can be done.

  Another technical challenge that must be addressed by the uplink packet 830 is that the frequency of the sending device must be synchronized. There are several options for accommodating frequency offset synchronization between STAs in a UL-OFDMA system, such as uplink packet 830. First, each STA can calculate its frequency difference and correct it. For example, the STA may calculate a frequency offset for the AP based on the UL-OFDMA announcement message sent to the STA. Based on this message, the STA can apply a phase ramp to the time domain uplink signal. The AP can also use the LTF to estimate the common phase offset for each STA. For example, the LTF transmitted by the STA can be orthogonal in terms of frequency. Thus, the AP can use a windowed inverse fast Fourier transform (IFFT) function to isolate the STA impulse response. Variation of these impulse responses across two identical LTF symbols can give a frequency offset estimate for every user. For example, a frequency offset in the STA can result in a phase ramp over time. Thus, if two identical LTF symbols are transmitted, the AP uses the difference between these two symbols to calculate the phase gradient across the two impulse responses in order to obtain an estimate of the frequency offset. It may be possible to do. This approach may be similar to the tone interleaving approach proposed in UL-MU-MIMO messages that may be known to those skilled in the art.

  FIG. 13 shows a process flow diagram for an exemplary method for transmitting high efficiency packets to two or more wireless communication devices. This method may be performed by a device such as an AP.

  At block 905, the AP transmits a legacy preamble that includes sufficient information to inform the legacy device to defer the packet. For example, the legacy preamble can be used to alert a legacy device to postpone a packet. Legacy packets may include reserved bits or a combination of reserved bits. These reserved bits may alert the high efficiency device to continue to listen for packets for the high efficiency preamble while also deferring the packet to the legacy device. In some aspects, means for transmitting the legacy preamble may comprise a transmitter, the legacy preamble including sufficient information to inform the legacy device to defer the packet.

  At block 910, the AP transmits a high efficiency signal, the high efficiency signal includes tone allocation information, and the tone allocation information identifies two or more wireless communication devices. In some aspects, the high efficiency signal may include tone allocation information that may include information identifying the STAs that will receive the information in the packet, and which subbands are intended for those STAs. STA can be warned. In some aspects, the high efficiency packet may also include sufficient information to cause the 802.11ac device to defer the packet. In some aspects, means for transmitting a high efficiency signal may comprise a transmitter, the high efficiency signal including tone allocation information, wherein the tone allocation information identifies two or more wireless communication devices. In some aspects, the high efficiency signal may further comprise an indication that several spatial streams may be assigned to each of the two or more wireless communication devices. For example, each of the two or more wireless communication devices may be assigned one or more spatial streams. In some aspects, means for assigning one or more spatial streams to each of the two or more wireless communication devices may comprise a transmitter or processor.

  At block 915, the AP transmits data to two or more wireless communication devices simultaneously, and the data is included on two or more subbands. For example, the AP can send data to up to four STAs. In some aspects, means for simultaneously transmitting data to two or more wireless communication devices may comprise a transmitter, where the data is included on two or more subbands.

  In some aspects, an AP may transmit a hybrid packet that includes data for both a legacy device, such as an IEEE 802.11a / n / ac device, and data for one or more high efficiency devices. Such hybrid packets may enable more efficient use of bandwidth in a mixed environment that includes both legacy and high efficiency devices. For example, in legacy systems, if an AP is configured to use 80 MHz, and the AP is sending packets to a device that cannot use all 80 MHz, the bandwidth allocated to that AP Some can be unused. This is one problem that is addressed by the use of high efficiency packets. However, in an environment where some of the STAs are highly efficient and some of the STAs are legacy devices, the legacy devices that cannot use the full bandwidth configured for use by the AP When transmitting, the bandwidth can still be unused. For example, as discussed above, high efficiency packets in such a system can use the full bandwidth, whereas legacy packets do not. Thus, a high efficiency device provides a hybrid packet that allows a legacy device to receive information in a portion of the packet's bandwidth, while a high efficiency device can receive information in another portion of the packet. It can be beneficial. Some of such packets can send data in legacy compliant formats, such as IEEE 802.11a / n / ac, and some of the packets can send data to high efficiency devices, such as Packets may be referred to as hybrid packets.

  An exemplary hybrid packet 1400 is shown in FIG. Such a hybrid packet may be transmitted by a wireless device, such as an AP. The hybrid packet may include a legacy portion where data is transmitted to the legacy device and a high efficiency portion where data is transmitted to the high efficiency device.

  Hybrid packet 1400 may include several legacy preambles, each duplicated through a portion of the packet bandwidth. For example, the exemplary hybrid packet 1400 is shown as an 80 MHz packet that includes four 20 MHz legacy preambles that are duplicated through the 80 MHz bandwidth of the packet 1400. Such duplication can be used in legacy formats to ensure that other devices that can operate on only a portion of the 80 MHz band postpone the packet. In some aspects, each of the devices in the network can monitor only the primary channel by default.

  The hybrid packet 1400 may include an L-STF 1405 and an L-LTF 1410 that are the same as those specified in the legacy format, such as IEEE 802.11a / n / ac. These fields can be the same as discussed above. However, the L-SIG 1415 of the hybrid packet 1400 may be different from the L-SIG of the legacy packet. L-SIG 1415 may include information used to signal the high efficiency device that the packet is a hybrid packet. In order for the legacy device to be able to receive information in the packet, this information must be hidden from the legacy device so that the information does not interrupt its reception of the L-SIG 1415.

  The L-SIG 1415 can signal the high-efficiency device that the packet is a hybrid packet by arranging the 1-bit code orthogonal to the information in the L-SIG 1415. For example, as discussed above, a 1-bit code may be placed on the Q-rail of L-SIG 1415. Legacy devices may not be aware of its 1-bit code and may be able to read L-SIG1415 as usual, but high-efficiency devices specifically look for this 1-bit code and it exists. It may be possible to determine whether or not. This 1-bit code can be used to signal a high efficiency device that a hybrid packet is being sent. In some aspects, the 1-bit code may be hidden from a legacy device that may not be configured to look for that code, or may not be visible to the legacy device. In some aspects, legacy devices may be able to understand L-SIG 1415 without observing any irregularities due to the presence of a 1-bit code. In some aspects, only the L-SIG 1415 in the primary channel may include a 1-bit code to instruct the high efficiency device to examine other channels for the HE-SIG 1425. In some aspects, some L-SIGs 1415 may have this 1-bit indicator, where the number of L-SIGs 1415 with that indicator is the number of channels to be used for legacy packets. equal. For example, if a legacy packet will contain both a first channel and a second channel, but not a third channel, L-SIG in the first channel and in the second channel May include a 1-bit indicator, but the L-SIG in the third channel does not include this indicator. The high efficiency device may be configured to examine a first channel having an L-SIG that does not include a 1-bit code and monitor that channel for the presence of HE-SIG 1425. In some aspects, the bandwidth information in VHT-SIG-A 1420 relates to how much bandwidth the legacy packet 1430 will use, and thus on what bandwidth the HE packet 1435 may start. Information can be included. In some aspects, the 1-bit code may only be included in the L-SIG 1415 being transmitted in the channel that will be used to transmit data to the HE device. For example, if a first channel is used to transmit to a legacy device and three other channels are used to transmit to a HE device in a particular packet, transmit in these three other channels Each of the L-SIGs 1415 may include a 1-bit code. In some aspects, within the HE packet, each L-SIG 1415 may include a 1-bit code to indicate that each channel may be used to transmit data to the HE device. In some aspects, this may allow the bandwidth used for the HE portion of the HE packet or hybrid packet to be signaled using the L-SIG 1415 of the packet. If the bandwidth used for the HE portion of the packet is signaled in the L-SIG 1415, this means that the HE-SIG 1425 in the HE packet or in the hybrid packet is the larger portion of the bandwidth allocated to the HE portion of the packet. May be possible. For example, the HE-SIG 1425 may be configured to span the bandwidth allocated for HE packets. In some aspects, rather than using only 20 MHz for HE-SIG 1425, using more bandwidth for HE-SIG 1425 means that more information is transmitted within HE-SIG 1425. Can be possible. In some aspects, the first symbol of HE-SIG 1425 may be transmitted redundantly on each 20 MHz of bandwidth allocated to the HE portion of the packet, whereas the remaining symbols of HE-SIG 1425 May be transmitted using the full bandwidth allocated for the HE portion of the packet. For example, the first symbol of HE-SIG 1425 may be used to transmit the bandwidth allocated to the HE portion of the HE packet or hybrid packet, so subsequent symbols are assigned to the HE portion of the packet. Over the entire bandwidth.

  As soon as the 1-bit code in L-SIG 1415 is received, the high efficiency device is configured to look in the high bandwidth portion of the bandwidth allocated to the AP, such as a high bandwidth channel, in order to find HE-SIG 1425. obtain. For example, upon receiving L-SIG 1415 with a 1-bit code in the orthogonal direction within hybrid packet 1400, the high efficiency device may be transmitted along with the legacy packet in other frequency bands, such as HE-SIG 1425, HE. -Can be configured to look in a 20 MHz channel separate from the channel that carries data to legacy devices for SIG. For example, in the exemplary hybrid packet 1400, HE-SIG 1425 is shown as being transmitted simultaneously with VHT-SIG-A 1420. In this example, the hybrid packet 1400 may include an IEEE 802.11ac compatible packet on the lower part of the bandwidth and a high efficiency packet on the upper part of the bandwidth. The hybrid packet 1400 may also include an IEEE 802.11a compatible packet or an IEEE 802.11n compatible packet in the lower part. Importantly, regardless of what type of packet the lower part is, the L-SIG 1415 signals to the high efficiency device that the packet is a hybrid packet, and thus is HE- It may be configured to include sufficient signaling information to look for SIG 1425.

  In some aspects, the HE-SIG 1425 may be similar to the previous high efficiency signal field discussed previously. In some aspects, an AP that transmits both high-efficiency packets and hybrid packets may use HE-SIG 1425 rather than using 1-bit signaling in the Q-rail to indicate that the packet is a high-efficiency packet. Symbols with rotating BPSK constellation (QBPSK) symbols can be used, but using a 1-bit signal on the Q-rail is instead a hybrid, such as a hybrid packet 1400 This is because it can be used to signal that it is a packet. For example, HE-SIG 1425 is used to inform a high efficiency device which one or more devices can receive information in the packet, such as by using a group ID, as discussed above. Can be done. Thus, the high efficiency device may be configured to receive and decode L-STF 1405, L-LTF 1410, and L-SIG 1415. If L-SIG 1415 includes a 1-bit code, the high efficiency device positions HE-SIG 1425 in a higher frequency band to determine whether the high efficiency portion of the hybrid packet includes information about that particular device. It can be configured to identify and decode.

  In some aspects, legacy packets may occupy only 20 MHz of bandwidth, as shown. However, the legacy portion of the packet 1400 may occupy different amounts of bandwidth as well. For example, the legacy portion of the hybrid packet may comprise 40 MHz, 60 MHz, 80 MHz, or other size legacy packets, while the high efficiency portion of the hybrid packet 1400 uses the remaining portion of available bandwidth can do. In some aspects, channel sizes other than 20 MHz may also be used. For example, the channel may be 5 MHz, 10 MHz, 15 MHz, 40 MHz, or other size. In some aspects, following legacy VHT-SIG-A 1420, legacy packet 1430 may be transmitted to the legacy device on the primary channel. In some aspects, legacy packet 1430 may include at least a primary channel and may include additional channels. For example, this legacy packet 1430 may be compatible with an IEEE 802.11a device, an 802.11n device, or an 802.11ac device. In some aspects, following one or more HE-SIGs 1425, the high efficiency packet 1435 is transmitted to one or more high efficiency devices using at least a portion of the bandwidth available to the AP. obtain. In some aspects, legacy packets may be sent to multiple legacy devices. For example, the hybrid packet may comprise a MU-MIMO 802.11ac packet that is sent to two or more 802.11ac compatible STAs.

  FIG. 15 shows an exemplary method 1500 for transmitting a hybrid packet. The method may be performed by a wireless device such as an AP.

  At block 1505, the AP transmits to one or more first devices in a first portion of bandwidth, where the one or more first devices have a first set of capabilities. In some configurations, the one or more first devices may be legacy devices. In some aspects, the first portion of bandwidth may be a primary channel. In some aspects, the means for transmitting to the first device may be a transmitter.

  At block 1510, the AP transmits simultaneously to one or more second devices in a second portion of bandwidth, where the one or more second devices have a second set of capabilities. Here, the transmission comprises a preamble that includes an indication for a device having a second capability set to locate a frequency band in which symbols including a set of transmission parameters for a device having the second capability set are sent. In this case, the indication is sent so as not to have a substantial effect on the preamble decoding of the device having the first capability set. In some aspects, the means for transmitting to the one or more second devices may be a transmitter. In some aspects, the preamble may be a legacy preamble and the indication may be a 1-bit code in L-SIG in the legacy preamble. In some aspects, the indication may be included in the L-SIG in the primary channel, in the primary channel and one or more other channels, or in other channels.

  FIG. 16 illustrates an exemplary method for receiving a hybrid packet. In some aspects, the method may be used by a STA, such as a high efficiency wireless communication device.

  At block 1605, the STA receives a legacy preamble in the primary channel. In some aspects, the means for receiving a legacy preamble may be a receiver.

  At block 1610, the STA determines whether the legacy preamble includes sufficient information to inform the high efficiency device to locate the high efficiency signal field in the one or more primary channels. In some embodiments, the means for determining can be a processor or a receiver.

  At block 1615, the STA receives the high efficiency signal field on at least one of the one or more non-primary channels. In some aspects, the means for receiving the high efficiency signal field may be a receiver. In some aspects, the STA may further receive data on at least one of the one or more non-primary channels. In some aspects, the means for receiving data may be a receiver.

(High-efficiency signal field delay spread protection and potential structure)
In some aspects, an outdoor or other wireless network may have a channel with a relatively high delay spread, such as over 1 μs. For example, access points at high elevation angles, such as pico / macrocell tower access points, may have a high delay spread. Various wireless systems, such as with 802.11a / g / n / ac, use a cyclic prefix (CP) length of only 800 ns. Nearly half of this length can be consumed by the transmit and receive filters. Due to this relatively short CP length and the overhead from transmit and receive filters, such 802.11a / g / n / ac networks may not be suitable for outdoor deployments with high delay spread.

  According to aspects of the present disclosure, a packet format that is backward compatible with such legacy systems and that supports cyclic prefixes longer than 800 ns that may allow the use of 2.4 GHz and 5 GHz WiFi systems in outdoor deployments. (PHY waveform) is provided.

  For example, one or more bits of information are embedded in one or more of L-STF, L-LTF, L-SIG, or in another part of the packet preamble, such as HE-SIG. It is possible. These one or more bits of information may be included for a device configured to decode them as described above, but a legacy (eg, 802.11a / g / n / ac) receiver Does not affect decryption by. These bits may include indication of the packet including delay spread protection to allow use of such a packet in an outdoor setting or in another setting with a potentially high delay spread.

  In some aspects, some methods may be used to provide delay spread protection or delay spread tolerance. For example, different transmission parameters may be used to increase the symbol duration (eg, downclocking to reduce the sample rate, or increasing the FFT length while maintaining the same sample rate) . Increasing the symbol duration, such as only 2x or 4x, may increase the tolerance for higher delay spread.

  In some aspects, the increased symbol duration may be signaled in the L-SIG or HE-SIG field. In some aspects, other packets on the network may not include signaling for increased symbol duration, but rather may be packets with conventional or “normal” symbol duration. Maintaining a “normal” symbol duration may be desirable in some cases, but this means that increased symbol duration generally means increased FFT size, and thus to frequency error and increased PAPR. This is because it means increased sensitivity. Moreover, not all devices in the network require this increased delay spread tolerance. Thus, in some cases, the increased FFT size may impair performance, and therefore it may be desirable for some packets to use conventional symbol duration.

  Thus, in some aspects, all packets may include an increased symbol duration after the L-SIG field or the HE-SIG field. In other aspects, only packets containing information signaling increased symbol duration in L-SIG or HE-SIG may include increased symbol duration. In some aspects, signaling for increased symbol duration may be included in the HE-SIG field, and the L-SIG field, VHT-SIG-A field, or another field in the packet. In some aspects, this signaling may be conveyed by Q-BPSK rotation within a symbol of the SIG field, eg, L-SIG or HE-SIG. In some aspects, this signaling may be communicated by hiding information in orthogonal rails, such as the imaginary axis of the packet's field.

  In some aspects, the increased symbol duration may be used for either or both uplink packets or downlink packets. For uplink packets, the AP can signal in the preceding downlink packet that the uplink packet can be transmitted using the increased symbol duration. For example, in an uplink OFDMA packet, the AP may send a tone allocation message telling the user to use a longer symbol duration. In this case, the uplink packet itself may not need to carry an indication indicating a particular symbol duration. In some aspects, the AP to STA signal may inform the STA to use a particular symbol duration in all future uplink packets unless otherwise specified.

  In some aspects, such delay spread protection may be incorporated into a high efficiency packet as described above. The preamble format presented herein allows for legacy devices to detect whether a packet is an 802.11n packet, an 802.11a packet, or an 802.11ac packet while delaying. Providing a scheme in which spreading protection can be included in the packet.

  The preamble format presented herein can maintain L-SIG based delay as in the case of IEEE 802.11ac (mixed mode preamble) packets. Making the legacy section of the preamble decodable by an 802.11a / an / ac station may facilitate mixing legacy and HE devices in the same transmission. The preamble format provided herein can help provide protection on the HE SIG, which can help achieve robust performance. For example, these preamble formats can help reduce the SIG error rate to less than 1% in relatively strict standard test scenarios.

  FIG. 17 illustrates a packet having one exemplary HE preamble format in accordance with aspects of the present disclosure. This exemplary HE preamble format can be compared to the VHT preamble format. As shown, the HE preamble format includes one or more signal (SIG) fields decodable by a first type of device (eg, 802.11a / ac / n device) and a second type of device ( For example, it may include one or more SIG fields (HE-SIG1) decodable by the HE device). As shown, 802.11 / ac / n devices can be deferred based on the duration field in the L-SIG. L-SIG may be followed by repeated high efficiency SIG (HE-SIG) fields. As shown, after repeated HE-SIG fields, the device can already know if the packet is a VHT packet, and therefore there may not be a VHT-STF gain setting problem.

  In this exemplary format shown in FIG. 17, the HE-SIG1 field may be repeated and preceded by a normal guard interval (GI) that provides protection for HE-SIG1 for the HE device. With repeated HE-SIG1, this packet may have a lower signal-to-noise ratio operating point and thus provide more robust protection from inter-symbol interference (ISI). In some aspects, the L-SIG may transmit at 6 Mbps as packet type detection based on the Q-BPSK check for two symbols after the L-SIG is unaffected.

  As discussed above, various techniques may be used to signal HE packets to the HE device. For example, the HE packet may be signaled by placing an orthogonal rail indication in the L-SIG based on a CRC check in HE-SIG1 or based on a repetition of HE-SIG1.

  Delay spread protection on HE-SIG2 can take various forms. For example, HE-SIG2 may be transmitted over 128 tones (within 20 MHz) to provide additional delay spread protection. This may result in a guard interval of 1.6 us, but may require interpolation of the channel estimates calculated based on the L-LTF that would include the conventional number of tones. As another example, HE-SIG2 may have the same symbol duration, but may be sent with a 1.6 us cyclic prefix. This can result in more cyclic prefix overhead than the traditional 25% value, but may not require interpolation. In one aspect, HE-SIG2 may be sent through the full bandwidth rather than repeating every 20 MHz. This may require that bandwidth bits be placed in HE-SIG1 to indicate full bandwidth.

  FIG. 18 illustrates a packet having another exemplary HE preamble format in accordance with aspects of the present disclosure. Similar to FIG. 17, this exemplary HE preamble format is compared to the VHT preamble format. As described above, the IEEE 802.11a / ac / n device can defer packets based on the duration field in the L-SIG. L-SIG may be followed by repeated high efficiency SIG (HE-SIG) fields. In the exemplary format shown in FIG. 18, the HE-SIG1 field may be repeated, while the first HE-SIG1 field is preceded by a normal guard interval, whereas the second HE-SIG1 is normal. Preceding the guard interval.

  This iteration of HE-SIG1 where the guard interval is inserted before the first HE-SIG1 and after the second HE-SIG1 may provide protection to the HE device. It will be noted that the central part of the HE-SIG1 section may look like a HE-SIG1 symbol with a relatively large CP. In this aspect, the Q-BPSK check for the first symbol after L-SIG is not affected. However, the Q-BPSK check on the second symbol may give random results due to the guard interval after the second HE-SIG1. However, these random results may not have an adverse effect on the VHT device. For example, the VHT device may classify the packet as an 802.11ac packet, but at this point the device can attempt to perform a VHT-SIG CRC check, which will fail. Thus, despite the random results of the Q-BPSK test on the second signal after L-SIG, the VHT device will still postpone this packet.

  These packets may still carry 6 Mbps because the auto-discovery process for legacy devices, such as VHT devices (compatible with IEEE 802.11ac), will cause those devices to defer the packets of FIG. Similar to the packet of FIG. 17, a number of techniques discussed above may be used to signal the HE device that the packet is a HE packet. Similarly, information regarding the packet's delay spread protection may be provided to the HE device in several ways, such as a field included in HE-SIG2.

  FIG. 19 illustrates a packet having another exemplary HE preamble format in accordance with aspects of the present disclosure. As described above, this exemplary HE preamble format is similar to the 802.11ac VHT preamble format. As shown, the 802.11a / ac / n device can defer packets based on the duration field in the L-SIG. L-SIG may be followed by repeated high efficiency SIG (HE-SIG) fields.

  In the exemplary format shown in FIG. 19, the repeated HE-SIG1 field may be preceded by a double guard interval (DGI). Use of such a double guard interval may result in random results of Q-BPSK checking for the first symbol after L-SIG. Therefore, some legacy devices may not defer this packet when the L-SIG signals a 6 Mbps rate. Thus, the L-SIG in such a packet may need to signal rates other than 6 Mbps to ensure that all IEEE 802.11a / ac / n devices defer the packet. For example, L-SIG can signal a rate of 9 Mbps. Techniques similar to those discussed above can be used to signal that the packet is a HE packet and can be used to signal whether the packet includes delay spread protection.

  Various optimizations may be provided for the preamble format, such as the preamble formats shown in FIGS. For example, for the exemplary formats shown in FIGS. 18 and 19, it may be possible to truncate the second HE-SIG1 symbol and start the next symbol early to save overhead. In addition, there may be some benefit in having SIG-B after HE-LTF that can provide per-user bits for MU-MIMO.

  FIG. 20 shows an exemplary bit allocation for the HE-SIG-1 field. 2 to 3 bits for BW indication, 8 bit length indication, 1 bit to indicate that longer symbols are used, 2 to 3 reserved bits, 4 bits for CRC, as shown There may be 6 and 6 tail bits. If the Longer Symbols ON bit is provided in HE-SIG1, this is either HE-SIG2 has delay spread protection or everything after HE-SIG2 uses an increased FFT size Can be used to signal. The above-described HE-SIG format where HE-SIG is configured with HE-SIG1 and HE-SIG2 may allow for delay spread protection and may be used in packets that allow multiple access, such as OFDMA packets.

(Uplink packet with legacy preamble)
FIG. 21 shows an exemplary structure of an uplink physical layer packet 2100 that can be used to enable backward compatible multiple access wireless communications. In general, in an uplink message, the legacy preamble may not be required because the NAV is set by the first downlink message of the AP. The AP's initial downlink message can cause the legacy device on the network to postpone the uplink packet. However, some wireless devices may be outside the range of the AP, but may be within the range of the STA that is transmitting to the AP. Thus, if these devices are legacy devices, they may not defer the AP because they did not receive the AP's initial downlink message. These devices also do not defer uplink packets, such as the uplink packet of FIG. 12, because they do not have a legacy pre-angle that the legacy device can recognize. Thus, transmission of such devices may interfere with uplink packets, and therefore it may be desirable to transmit uplink packets that include sufficient legacy preambles to prevent the legacy device from deferring the packets. These uplink packets can take several possible forms. Uplink packet 2100 is an exemplary uplink packet that includes a legacy preamble. Note that although packet 2100 includes time for each portion of the packet, these times are merely examples. Each portion of the packet 2100 may be longer or shorter than shown. In some aspects, the legacy portion of the preamble, such as L-STF, L-LTF, and L-SIG, to allow the legacy device to decode the legacy portion of the preamble and postpone the packet 2100. May be advantageously the time listed.

  Thus, the packet 2100 can be used to inform such legacy device to defer uplink packets by providing a legacy preamble that such legacy device can recognize. This legacy preamble may include L-STF, L-LTF, and L-SIG. As in packet 830, each transmitting device may be configured to transmit its own preamble on its allocated bandwidth. These legacy preambles can protect uplink communications from nodes that did not listen to the AP's initial downlink message.

  As in packet 830, each of several devices, here N devices, can transmit simultaneously within its allocated bandwidth. Following the legacy preamble, each device can transmit a high efficiency preamble on its assigned tone. For example, each device can transmit a HE-SIG on its own assigned tone. Following this HE-SIG, each device can then transmit a HE-STF and can transmit one or more HE-LTFs. For example, each device can send a single HE-STF, but can send several HE-LTFs corresponding to the number of spatial streams assigned to that device. In some aspects, each device may transmit several HE-LTFs corresponding to the number of spatial streams assigned to the device with the largest number of spatial streams. This allocation of spatial streams may be done, for example, in the AP's initial downlink message. If each device sends the same number of HE-LTFs, this may reduce the peak-to-average power ratio (PAPR). Such a reduction in PAPR may be desirable. Furthermore, if each device transmits the same number of HE-LTFs, this may make it easier for the AP to process the received packets. For example, if different numbers of HE-LTFs are sent by each device, the AP can receive data from another device at the same time it receives a preamble for one device. This can make it more complicated for the AP to decode the packet. Thus, it may be preferable to use the same number of HE-LTFs for each device. For example, each of the transmitting devices may be configured to determine the maximum number of spatial streams that any device is receiving and transmit a number of HE-LTFs corresponding to that number.

  In some aspects, the L-STF in such a packet may include a small cyclic shift of up to approximately 200 ns. Large cyclic shifts can cause problems in such L-STFs for legacy devices that may use cross-correlation based detection algorithms. The HE-STF in such a packet 2100 may include a larger cyclic shift on the order of approximately 800 ns. This may allow for a more accurate gain setting within the AP receiving the uplink packet 2100.

  FIG. 22 shows another example structure of an uplink physical layer packet 2200 that may be used to enable backward compatible multiple access wireless communications. This packet 2200 may be similar to packet 2100, but within this packet 2200, each of the transmitting devices cannot transmit the HE-STF. Instead, each of the transmitting devices can transmit the L-STF with a larger cyclic shift, such as on the order of approximately 800 ns. This may affect legacy devices in the case of cross-correlation packet detection, but this may allow the packet to be shorter because it may allow the transmitting device not to transmit the HE-STF. Although packet 2200 includes time for each portion of the packet, these times are merely examples, and each portion of the packet may be longer or shorter than shown. In some aspects, the legacy portion of the preamble, such as L-STF, L-LTF, and L-SIG, to allow the legacy device to decode the legacy portion of the preamble and postpone the packet 2200. May be advantageously the time listed.

  Within packet 2200, each device may transmit several HE-LTFs corresponding to the number of spatial streams assigned to that device. In some aspects, each device may instead transmit several HE-LTFs corresponding to the number of spatial streams assigned to the device to which the maximum number of spatial streams is assigned. As discussed above, such an approach can reduce PAPR.

  In some aspects, a longer symbol duration may provide delay spread protection and protection from timing offsets. For example, devices that send uplink packets may not start sending packets at the same time, but instead may start at slightly different times. Longer symbol duration may also assist the AP in interpreting packets in such cases. In some aspects, the device may be configured to transmit with a longer symbol duration based on a signal in the AP downlink trigger message. In some aspects, for greenfield packets, such as packet 830, there is no need for legacy compatibility, so the entire waveform may be transmitted with a longer symbol duration. Within an uplink packet that includes a legacy preamble, such as packet 2100 or 2200, the legacy preamble may be transmitted with a conventional symbol duration. In some aspects, the later portion of the legacy preamble may be transmitted with a longer symbol time period. In some aspects, longer symbol duration may be achieved by using an existing IEEE 802.11 tone plan within a smaller band. For example, a smaller subcarrier spacing may be used, sometimes referred to as down-clocking. For example, the 5 MHz portion of the bandwidth can use a 64-bit FFT 802.11a / n / ac tone plan, while 20 MHz can be used normally. Thus, each tone may be 4 × longer in such a configuration than in a typical IEEE 802.11a / n / ac packet. Other durations can also be used. For example, it may be desirable to use twice as long tones in a typical IEEE 802.11a / n / ac packet.

  FIG. 23 shows an exemplary method 2300 for receiving a packet. The method may be performed by a wireless device such as an AP.

  At block 2305, the AP receives a first portion in a first section of bandwidth, the first portion is transmitted by a first wireless device, and the first portion is to postpone the packet. A legacy section of the first preamble that includes sufficient information to inform the legacy device and a high efficiency section of the first preamble. In some aspects, the means for receiving may be a receiver.

  At block 2310, the AP receives the second portion in the second section of bandwidth simultaneously, the second portion is transmitted by the second wireless device, the second portion defers the packet A second preamble section including sufficient information to inform the legacy device and a second high efficiency section of the second preamble. In some aspects, the means for receiving simultaneously may be a receiver. In some aspects, the first wireless device and / or the second wireless device may transmit on several spatial streams. In some aspects, the high efficiency portion of the preamble transmitted by the first wireless device and the second wireless device may include a number of long training fields. In some correspondences, the number of long training fields may be based on the number of spatial streams assigned to a particular device, or the highest number of spatial streams assigned to any wireless device.

  In some aspects, it may be desirable for an OFDMA packet to have a structure that more closely mimics the structure of an uplink multi-user multiple-input multiple-output (MU-MIMO) packet. For example, some preceding packets, such as packet 2100 of FIG. 21, may include a HE-SIG prior to one or more HE-LTFs. Similarly, within the packet 830 of FIG. 12, each transmitting device transmits a single HE-LTF, followed by an HE-SIG, followed by the remaining number of HE-LTFs. However, in order to have an uplink packet with a structure more similar to an uplink MU-MIMO packet, it may be desirable for the HE-SIG to have a packet that follows all HE-LTFs in the packet.

  Therefore, it may be possible to send HE-SIG following all HE-LTFs in any of the described packets. In some aspects, when HE-SIG follows all HE-LTFs, it may be desirable to find another way to signal the number of spatial streams being used by each transmitting device in the uplink packet. . For example, in some of the previously described packets, the first HE-LTF from the transmitting device provides sufficient information to allow the AP to decode the HE-SIG from that transmitting device. May be included. In some of the previously described packets, the HE-SIG from the transmitting device may include information regarding the number of spatial streams being used by that device in the packet, and thus in some aspects HE -SIG may indicate the number of HE-LTFs that will be transmitted by the transmitting device. However, if the HE-SIG is transmitted following each HE-LTF, it may be desirable to indicate the number of spatial streams used by the transmitting device in a different manner. For example, the number of spatial streams used by the transmitting device may be indicated in a downlink message from the AP. For example, an uplink OFDMA packet may be sent in response to a downlink packet from the AP that indicates which devices may transmit on the uplink OFDMA packet. Thus, this downlink packet can also assign several spatial streams to each device.

  FIG. 24 is an exemplary uplink packet structure in which HE-SIG is transmitted after each HE-LTF. Within uplink OFDMA packet 2400, each of the transmitting devices may transmit HE-STF 2410 as in the other packets described above. Following the HE-STF 2410, each of the transmitting devices may transmit several HE-LTFs 2420. Each transmitting device may transmit a number of HE-LTFs 2420 corresponding to the number of spatial streams being used by that transmitting device. For example, if a transmitting device is using two spatial streams, the device can transmit two HE-LTFs 2420. Following transmitting all of its HE-LTF 2420, each transmitting device then transmits HE-SIG 2430. This HE-SIG 2430 may include information similar to that described above.

  As shown, in packet 2400, each transmitting device transmits a number of HE-LTFs 2420 corresponding to the number of spatial streams being used by that device. As discussed above, in some other aspects, the number of spatial streams being used by a device may be indicated in the HE-SIG sent by that device. However, because this indication may arrive too late for the AP to predict the number of HE-LTFs 2420 that the transmitting device may transmit, the number of spatial streams within the packet 2400 is HE-SIG2430. May not be included. Thus, other ways in which the AP determines the number of spatial streams from a given event can be used. For example, a downlink message from an AP, such as a message that triggers an uplink OFDMA packet 2400, can assign several spatial streams to each transmitting device. An exemplary downlink message from the AP including information regarding how many spatial streams each transmitting device can use is shown in FIG. In some aspects, the number of spatial streams used by each transmitting device may be determined in other ways as well. For example, the number of spatial streams for each transmitting device may be communicated in periodic downlink messages, such as in beacons. In some aspects, the AP may be configured to determine the number of spatial streams based on received packets 2400. For example, the AP analyzes each incoming packet 2400 and detects the end point of the HE-LTF 2420 and the start point of the HE-SIG 2430, without any prior knowledge of how many spatial streams can be transmitted by each transmitting device. It may be configured to determine the number of HE-LTFs 2420 that are being transmitted. Other methods may be used to allow the AP to determine the number of spatial streams, and thus the number of HE-LTFs 2420 being transmitted by each device within the packet 2400. Following the HE-SIG 2430 from each transmitting device, the device may transmit data 2440 that the device desires to transmit in the packet 2400. In some aspects, each device may transmit the same number of HE-LTFs 2420 in the packet 2400. For example, each transmitting device may transmit several HE-LTFs 2420 corresponding to the number of spatial streams assigned to the device to which the maximum number of spatial streams is assigned.

  FIG. 25 is another example uplink packet structure in which the HE-SIG is transmitted after each HE-LTF. Packet 2500 may correspond to a mixed mode packet in which each transmitting device transmits a legacy preamble prior to transmitting the high efficiency portion of the packet. Within packet 2500, each device initially transmits a legacy preamble that includes L-STF 2502, L-LTF 2504, and L-SIG 2506. These portions of packet 2500 may be transmitted as described above.

  After the legacy preamble, packet 2500 is similar to packet 2400. Each of the sending devices may send HE-STF 2510, followed by several HE-LTFs 2520, followed by HE-SIG 2530, followed by data 2540 that the sending device wishes to send to the AP. Each of these portions of the packet may be transmitted in a manner similar to that disclosed above. The number of HE-LTFs 2520 transmitted by each device may be based at least in part on the number of spatial streams transmitted by each device thereon. For example, a device transmitting on two spatial streams can transmit two HE-LTF 2520s.

  In some aspects, each device in the packet 2500 may transmit the same number of HE-LTF 2520s. For example, each of the transmitting devices may transmit a number of HE-LTFs 2520 that correspond to the maximum number of spatial streams being transmitted by any of the transmitting devices. Thus, within packet 2500, each transmitting device must have knowledge of how many HE-LTFs 2520 are transmitted within that packet. As mentioned above, this may be advantageous because having each transmitter transmit the same number of HE-LTF 2520 may reduce the PAPR of the packet. Such a reduction in PAPR may result in benefits for the AP that receives the packet 2500, as described above. If each transmitting device transmits the same number of HE-LTFs 2520 in the packet 2500, each of these devices should be aware of how many HE-LTFs 2520 are transmitted. This can be achieved in several ways. For example, the AP can send a downlink trigger message to the sending device. The trigger message may include information such as which devices can transmit in the uplink packet, the bandwidth allocated to each device, and the number of spatial streams allocated to each device. This trigger message may also indicate to the transmitting device how many HE-LTFs 2520 are to be included in the uplink packet 2500. For example, the downlink message may indicate to the transmitting device how many spatial streams each device may use. An exemplary downlink trigger message from the AP including information regarding how many spatial streams each transmitting device may use is shown in FIG. Similarly, the number of spatial streams assigned to each device may be constant. For example, a network may be constructed in which each device can use only two spatial streams. Similarly, the number of spatial streams assigned to each device may be conveyed in a message, such as in a beacon message periodically transmitted from the AP. Thus, the transmitting device may transmit several HE-LTFs 2520 that correspond to the number of spatial streams assigned to the device to which the most spatial streams are assigned. In some aspects, other methods may be used to adjust the number of HE-LTFs 2520 transmitted by each transmitting device.

  An exemplary downlink message 2600 from the AP is shown in FIG. 26 that includes information regarding how many spatial streams each transmitting device may use. This message 2600 may include trigger message information 2605. For example, this information 2605 may include timing information regarding when uplink messages may be sent. This information 2605 may further include information regarding whether the sending device should confirm receipt of the trigger message. Following this information 2605, downlink message 2600 may include device 1 identification 2610. This identification 2610 may be, for example, a unique number or value assigned to device 1 and identifying device 1. Downlink message 2600 may also include a number of streams 2615 assigned to device 1. For example, device 1 may be assigned two spatial streams. The downlink message may also include device 2 identification 2620, some spatial streams 2625 for device 2, device 3 identification 2630, and some spatial streams 2635 for device 3. In some aspects, other numbers of devices may be identified in the downlink message 2600. For example, two, three, four, five, six, or more devices may be identified in the downlink message 2600. Note that this downlink message 2600 is merely an example. Other information may also be included in the downlink trigger message and may be included in a different order or number than shown in the downlink message 2600.

  In some aspects, it may be advantageous to harmonize the LTF transmitted in the uplink OFDMA packet with the LTF transmitted in the UL MU-MIMO packet. For example, within a UL MU-MIMO packet, each sending device can send a message across all tones. Thus, the LTF in the UL MU-MIMO packet may need to contain sufficient information to allow the receiving STA to recognize the transmission from each transmitting STA on each tone, such as an AP. Such an LTF format may be used in both UL MU-MIMO packets and UL OFDMA packets.

  For example, one format that may be used for LTF in either UL MU-MIMO packets or UL OFDMA packets is to transmit P-matrix based LTFs. In this approach, the LTF may be transmitted by each of the transmitting STAs on each tone. The LTFs from each device can be transmitted in such a way that they are orthogonal to each other. The number of LTFs transmitted may correspond to the number of spatial streams assigned to all devices. For example, if two devices each transmit on one stream, two LTFs may be sent. In some aspects, within the first LTF, the value at a given tone may be equal to H1 + H2, where H1 is the signal from the first device and H2 is the signal from the second device. It is. At the next LTF, the value at a given tone may be equal to H1-H2. Thus, this orthogonality may allow the receiving device to identify the transmission of each of the two transmitting devices on each tone. Such a format for LTF has been used, for example, in previous IEEE 802.11 formats. However, one potential problem with P-matrix based LTFs is that if two or more transmitting devices have high frequency offsets relative to each other, those LTFs may not be effective. In that environment, LTF orthogonality may be lost, and thus the ability of the receiving device to properly decode the packet may be compromised. Thus, in some aspects it may be desirable to use different LTF formats for UL MU-MIMO packets and UL OFDMA packets.

  Another possible different LTF for UL MU-MIMO packets and UL OFDMA packets is to use tone interleaved LTFs or subband interleaved LTFs. As described above, the number of LTFs transmitted may correspond to the total number of spatial streams sent by all transmitting devices. Such an LTF format may be particularly useful when there is a large frequency offset between the various devices transmitting uplink packets. These LTF formats can be used in UL MU-MIMO packets. These LTF formats can also be used in UL OFDMA packets to coordinate UL OFDMA packets with UL MU-MIMO packets.

  FIG. 27 is a drawing 2700 of a tone interleaved LTF that may be used within a UL OFDMA packet. For example, these LTFs can be used in any of the previously described UL OFDMA packets. For example, there are four spatial streams in this packet. These spatial streams may be numbered, for example, spatial streams 1-4. Each spatial stream may be transmitted by a separate device, or one device may transmit more than one of the spatial streams. Thus, the four spatial streams may correspond to UL OFDMA packets being transmitted by two, three, or four devices. Since there are four spatial streams, four LTFs labeled LTF1 2705, LTF2 2710, LTF3 2715, and LTF4 2720 may be sent. Each LTF may include a number of tones, here numbered 1-8. Any number of tones may be included in the LTF corresponding to the number of tones included in the data portion of the UL OFDMA packet. Within this tone interleaved LTF, during LTF1 2705, the first stream may be transmitted on tones 1, 5, 9, etc. In some aspects, the spacing between these tones (ie, the 1 and 5 spacing) is based on the number of spatial streams. For example, in FIG. 2700, there are four spatial streams, so the interval between the tones that each stream transmits on is also four. During LTF1 2705, the second stream can be transmitted on tones 2, 6, 10, etc., while the third spatial stream can be transmitted on 3, 7, 11, etc. The fourth spatial stream can be transmitted on tones 4, 8, 12, etc. Within the next LTF, ie LTF2 2710, each spatial stream may be transmitted on a tone that is one tone higher than the previous LTF. For example, in LTF1 2705, stream 1 is transmitted on tones 1 and 5, while in LTF2 2710, stream 1 transmits on tones 2 and 5. Thus, after several LTFs equal to the number of spatial streams, each spatial stream may have transmitted on each tone. Using this tone interleaved LTF, the spatial streams do not transmit at the same frequency at the same time, so offset may cause no cross-stream leakage. For example, the offset can be a few kHz. In some aspects, it may be advantageous to repeat LTF1 2725 again after the last LTF to estimate the frequency offset for each stream. For example, LTF1 2705 may be the same as LTF1 2725. However, these two LTFs can be compared.

FIG. 28 is a drawing 2800 illustrating a subband interleaved LTF that may be used within a UL OFDMA packet. For example, these LTFs can be used in any of the previously described UL OFDMA packets. A UL OFDMA packet may include several spatial streams and may be transmitted on several tones. For example, the diagram 2800 includes four spatial streams. Since there are 4 spatial streams, 1 to N _SC tones are divided into 4 subbands, where N _SC is the total number of subcarriers excluding guard tones and DC tones. For example, if there are 64 tones, tones 1-16 can be subband 1, tones 17-32 can be subband 2, tones 33-48 can be subband 3, and tones 49-64. May be subband 4. In some aspects, the number of tones in each subband may be equal or approximately equal. In each of the four LTFs, each of the four spatial streams can be transmitted on its assigned subband tone. For example, within LTF1 2805, subband 1 may be assigned to spatial stream 1, subband 2 may be assigned to spatial stream 2, and so on. Within the subsequent LTF2 2810, each of the subbands may be assigned to a different spatial stream of the spatial stream. Thus, after four LTFs, each of the four spatial streams may have transmitted once on each of the four subbands.

  The LTF structure shown in FIGS. 2700 and 2800 may have several advantages. For example, this structure may provide better performance when there is a large frequency offset between uplink clients. In addition, these LTF structures will allow the AP to receive transmissions in each of the spatial streams on each of the tones. This may, for example, allow a spatial stream to switch from one tone to another if such a switch is desired. In addition, this may allow the AP to determine the signal strength of a given spatial stream for a given device on each tone. This will allow the AP to assign tones to devices based on which tone the device has the best signal in future packets. For example, if an AP assigns tones to different devices, the AP observes that one device has a lower signal-to-noise ratio for some tones and a stronger signal relative to other tones. Can do. Thus, the AP can assign those stronger tones to the device in future packets. FIG. 29 shows an exemplary LTF portion 2900 of a packet that may be transmitted within a UL OFDMA packet. For example, as described above, within a UL OFDMA packet, rather than assigning a tone within the SIG portion of the packet, the tone may be allocated elsewhere. For example, as described above, certain UL OFDMA packets can allocate tones from APs to transmitting devices in signaling messages, and the transmitting devices can allocate certain tones to certain devices. Thus, in the previous UL packet, the SIG may include MCS, code bits, and tone allocation information, but in some aspects, tone allocation information may not be included in the SIG field. Thus, the SIG field may only contain MCS and code bits, both of which comprise 6-7 bits of information, and binary convolutional coding (BCC), which may be 6 bits. Therefore, when transmitting a SIG feed that includes only 6-7 bits of information also includes 6 bits of CRC information as overhead, transmitting such SIG fields may be inefficient. Furthermore, in this case, it is not clear at all whether including such CRC information has sufficient benefits. Thus, it may be desirable to send the LTF portion 2900 of the packet, including MCS information 2910 and coding bits 2915. By including this information in the LTF portion of the packet, the packet may not need to include a SIG field at all.

  This information may be included in the LTF portion 2900 of the packet in several ways. For example, a signaling mechanism that can use non-coherent demodulation may be used. In some aspects, MCS information 2910 and coding bits 2915 may be included in the low strength code across some or all of the LTF tones. In some aspects, MCS information 2910 and code bits 2915 may be transmitted within a single LTF, such as LTF1 2825 or another LTF. In some aspects, MCS information 2910 and coding bits 2915 may be divided across each of the plurality of LTFs. For example, one or more bits of MCS information 2910 and coding bits 2915 may be included in more than one of the LTFs. Thus, in some aspects, this information may be required in the UL OFDMA packet because an explicit SIG field may be included in the packet's LTF.

  In general, a per-user SIG field may be included in the UL MU-MIMO packet after each LTF for that packet is transmitted. For example, this format may be similar to the format of packet 2400. However, HE-SIG may be included in the UL OFDMA packet prior to the packet STF or LTF, as shown in packet 2100. In some aspects, it may be desirable to transmit packets with SIG fields in both locations in order to match UL MU-MIMO packets with UL OFDMA packets. For example, a packet may be transmitted that includes a common SIG field preceding the HE-STF and also includes a per-user SIG field after all HE-LTFs.

  FIG. 30 shows a packet 3000 having a common SIG field prior to the HE-STF and a SIG field per user after all HE-LTFs. Packet 3000 shows that the packet includes a legacy preamble that includes a legacy short training field 3005, a legacy long training field 3010, and a legacy SIG field 3015. However, this packet can also be transmitted without such a legacy preamble. If such a preamble is included following the legacy preamble, the packet 3000 includes a common SIG 3020. In some aspects, this common SIG 3020 may include information similar to the information included in such SIG fields in previous UL OFDMA packets. For example, the common SIG may carry the number of spatial streams included in the OFDMA packet. For example, each transmitting device in a UL OFDMA packet may populate some of the common SIG 3020 tones. Subsequent to the common SIG 3020, HE-STF 3025 and HE-LTF 3030 are transmitted. These fields may be transmitted according to the above disclosure. For example, the HE-LTF 3030 can be based on the LFT format shown in FIGS. Any number of HE-LTFs 3030 may be transmitted. For example, the number of HE-LTFs 303 that can be transmitted can be based at least in part on the sum of the number of spatial streams that are part of the packet 3000. Following the HE-LTF 303, a second SIG field may be transmitted. This per-user SIG 3035 may be transmitted by each of the devices transmitting UL OFDMA packets. The format of the SIG field 3035 for each user can be based on the format of the SIG field in the UL MU-MIMO packet. Following the SIG field 3035 for each user, data 3040 may be transmitted. Thus, packet 3000 may include both a common SIG 3020 as in other UL OFDMA packets and a per-user SIG field 3035 as in other UL MU-MIMO packets. Since both SIG fields are included in the packet 3000, this packet format can be reused in both UL OFDMA and UL MU-MIMO.

  FIG. 31 shows an exemplary method 3100 for transmitting to one or more devices in a single transmission. The method may be performed by a wireless device such as an AP.

  At block 3105, the AP transmits a first section of the preamble according to the first format, the first section of the preamble notifying a device compatible with the first format to defer transmission. Contains enough information. For example, the first format may be a pre-existing format, such as a format defined by one or more of the existing IEEE 802.11 standards. In some aspects, the first format may be referred to as a legacy format. In some aspects, the first section of the preamble has a second set of capabilities and / or is compatible with the second format that another section of the preamble is transmitted to those devices. It may contain sufficient information to alert the device. In some aspects, the means for transmitting the first section may include a transmitter.

  At block 3110, the AP transmits a second section of the preamble according to a second format, the second section of the preamble includes tone allocation information, and the tone allocation information identifies two or more wireless communication devices. . For example, the second section of the preamble may comprise a high-efficiency preamble, and the second format may include an IEEE 802.11 format that is newer than the first format. In some aspects, the second section of the AP may identify two or more wireless communication devices, and each of those devices may be assigned one or more subbands of transmission bandwidth. In some aspects, the means for transmitting the second section may include a transmitter.

  At block 3115, the AP transmits data to two or more wireless communication devices simultaneously, and the data is included on two or more subbands. In some aspects, each of the subbands may be transmitted on a distinct and different non-overlapping portion of the transmission bandwidth. For example, each subband may correspond to a portion of the bandwidth of transmission, and each wireless communication device may be assigned to receive data on one or more of the subbands. Thus, an AP can transmit different data simultaneously to two or more different wireless communication devices in different subbands of the transmission band. In some aspects, the means for transmitting data may include a transmitter.

  FIG. 32 illustrates an example method 3200 for transmitting to one or more first devices having a first capability set and simultaneously transmitting to one or more second devices having a second capability set. Indicates. The method may be performed by a wireless device such as an AP.

  At block 3205, the AP transmits to the one or more first devices within the first portion of the bandwidth, and the one or more first devices have a first set of capabilities. In some aspects, this transmission may occur on the primary channel and may also occur on one or more secondary channels for a given band. In some aspects, a device having the first capability set may include a device that is compatible with certain IEEE 802.11 standards.

  At block 3210, the AP transmits simultaneously to one or more second devices within a second portion of bandwidth, where the one or more second devices have a second capability set, where In transmission, a device having a second capability set includes a preamble including an indication for locating a frequency band within a bandwidth for a symbol that includes a set of transmission parameters for a device having the second capability set. In this case, the indication is sent so as not to have a substantial effect on the preamble decoding of the device having the first capability set. For example, this indication may be a 1-bit code that is on the imaginary axis of part of the preamble. This indication may be sent at low power so that it does not interfere with the reception of the preamble by the device having the first capability set. In some aspects, the second capability set may be newer and more advanced than the first capability set. For example, a first capability set may correspond to a “legacy” format, while a second capability set may correspond to a “high efficiency” format. In some aspects, a device having a second capability set may be configured to search for an indication in the transmission and, if an indication is found, included in the second portion of bandwidth. May be configured to locate and receive the transmitted portion. In some aspects, transmissions within the second portion of bandwidth may correspond to the various types of high efficiency packets described above.

  In some aspects, this indication may be included as a 1-bit code in the preamble. In some aspects, the preamble may be transmitted redundantly across the transmission bandwidth. In some aspects, the indication may be included within a portion of the preamble. For example, this indication may be included in a replica of a preamble that is transmitted within a portion of the bandwidth that will include transmission to a device having a second capability set. In some aspects, means for transmitting to one or more first devices and means for transmitting simultaneously to one or more second devices may include a transmitter.

  FIG. 33 illustrates an example method 3300 for receiving a transmission that is compatible with both a device having a first capability set and a device having a second capability set. The method may be performed by a wireless device, such as a STA, having a second capability set.

  At block 3305, the STA receives the preamble within the first portion of the bandwidth, and the preamble is transmitted in a format compatible with the device having the first capability set. In some aspects, the first portion of bandwidth may include a primary channel, and may optionally include one or more secondary channels. In some aspects, the first capability set may include an IEEE 802.11 standard, such as IEEE 802.11a or 802.11ac. In some aspects, the means for receiving the preamble may include a receiver.

  At block 3310, the STA determines whether the preamble includes sufficient information to inform a device having the second capability set to locate a signal field in the second portion of the bandwidth, where Thus, the second portion of bandwidth does not overlap with the first portion of bandwidth. For example, as described above, the preamble may include an indication such as a 1-bit code on the imaginary axis in at least a portion of the preamble. Thus, the STA may be configured to determine whether this information is present in a given preamble. In some aspects, the second portion of bandwidth may include one or more secondary channels. In some embodiments, the means for determining whether the preamble includes information may include a processor or receiver.

  At block 3315, the STA receives the signal field within the second portion of the bandwidth. For example, this indication locates the second part of the bandwidth and gives the STA enough information to recognize that the signal field will be transmitted in the second part of the bandwidth. Can be provided. Thus, the STA can be configured to receive the signal field within this portion of the bandwidth. In some aspects, the signal field may be all or part of a preamble, such as a “high efficiency” preamble that is transmitted to a device having a second capability set within a second portion of bandwidth. . In some aspects, this may be on a portion of the bandwidth without the device having the second capability set interrupting the reception of the device having the first capability set on the first portion of the bandwidth. It may be possible to receive information from the AP or another device. Thus, as discussed above, this may allow a more complete use of bandwidth more times, so this will allow more efficient use of bandwidth that is available to the AP or another device. Can be possible. In some aspects, the means for receiving the signal field may include a receiver.

  FIG. 34 shows an exemplary method 3300 for receiving a transmission, some of which are transmitted by different wireless devices. The method may be performed by a wireless device such as an AP.

  At block 3405, the AP receives a first portion of transmission within a first section of bandwidth, where the first portion is transmitted by a first wireless device and includes a first preamble and first data. Including sections. In some aspects, the AP may have previously sent a message to the first wireless device informing the first wireless device about the time and bandwidth that the first wireless device can transmit to the AP. .

  At block 3410, the AP simultaneously receives a second portion of the transmission within the second section of bandwidth, the second section of bandwidth does not overlap with the first section of bandwidth, and the second Is transmitted by the second wireless device, and the second part includes a second preamble and a second data section. In some aspects, the first preamble and the second preamble may each include a training field. In some aspects, the number of training fields that each preamble includes may be based on the number of spatial streams assigned to a particular device. For example, a device that is assigned three spatial streams may send one short training field and three long training fields. Similarly, a device that is assigned one spatial stream can transmit one short training field and one long training field. In some aspects, each device may transmit several training fields based on how many spatial streams have been assigned to that particular device. In some aspects, it may be advantageous for each device to transmit the same number of spatial streams. For example, if each device transmits the same number of spatial streams, this can reduce the peak-to-average power ratio of the combined transmission, which can be advantageous. In some aspects, transmissions from the first wireless device and the second wireless device may be triggered by a message from the AP. This message can also indicate to each device how many spatial streams that device can transmit and can indicate the number of training fields each device should transmit.

  FIG. 35 illustrates various components that may be utilized within a wireless device 3502 that may be employed within the wireless communication system 100. Wireless device 3502 is an example of a device that may be configured to implement the various methods described herein. For example, the wireless device 3502 may comprise one of the AP 104 of FIG. In some aspects, the wireless device 3502 may comprise a wireless device configured to receive the packets described above.

  Wireless device 3502 may include a processor 3504 that controls the operation of wireless device 3502. The processor 3504 may be referred to as a central processing unit (CPU). Memory 3506, which may include both read only memory (ROM) and random access memory (RAM), provides instructions and data to processor 3504. A portion of memory 3506 may also include non-volatile random access memory (NVRAM). The processor 3504 normally performs logic and arithmetic operations based on program instructions stored in the memory 3506. The instructions in memory 3506 may be executable to implement the methods described herein. For example, memory 3506 may include instructions sufficient to allow wireless device 3502 to receive transmissions from high efficiency devices. For example, the memory 3506 enables the wireless device 3502 to receive a packet that includes a preamble for a device having a first capability set and a second preamble for a device having a second capability set. It can contain enough instructions. In some aspects, the wireless device 3502 includes a frame receiving circuit 3521 that can include instructions sufficient to allow the wireless device 3502 to receive a packet as described in the method 3300 and / or the method 3400. obtain. This frame receive circuit 3521 allows the device to receive a preamble within the first portion of bandwidth, as described in method 3300, to determine whether an indication exists, Sufficient instructions may be included to allow reception of the signal field within the portion of. In some aspects, the frame receive circuit 3521 can receive the first portion of the transmission within the first section of bandwidth and the second section of bandwidth as described in method 3400. Sufficient instructions to allow the second part of the transmission to be received at the same time.

  The processor 3504 may comprise or be a component of a processing system implemented with one or more processors. The one or more processors can be general purpose microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), controllers, state machines, gated logic, discrete hardware It may be implemented with any combination of components, dedicated hardware finite state machines, or any other suitable entity capable of performing information calculations or other operations.

  The processing system may also include a machine readable medium for storing software. Software shall be interpreted broadly to mean any type of instruction, whether referred to as software, firmware, middleware, microcode, hardware description language, or other terminology. . The instructions may include code (eg, in source code format, binary code format, executable code format, or any other suitable code format). The instructions, when executed by one or more processors, cause the processing system to perform various functions described herein.

  The wireless device 3502 may also include a housing 3508 that may include a transmitter 3510 and a receiver 3512 that allow transmission and reception of data between the wireless device 3502 and a remote location. Transmitter 3510 and receiver 3512 may be coupled to transceiver 3514. Antenna 3516 can be attached to housing 3508 and electrically coupled to transceiver 3514. The wireless device 3502 may also include multiple transmitters, multiple receivers, multiple transceivers, and / or multiple antennas (not shown).

  The wireless device 3502 can include a signal detector 3518 that can be used to detect and quantify the level of the signal received by the transceiver 3514. The signal detector 3518 can detect signals such as total energy, energy per subcarrier per symbol, power spectral density, and other signals. Wireless device 3502 may also include a digital signal processor (DSP) 3520 for use in processing signals. The DSP 3520 may be configured to generate a data unit for transmission. In some aspects, the data unit may comprise a physical layer data unit (PPDU). In some aspects, the PPDU is referred to as a packet.

  In some aspects, the wireless device 3502 may further comprise a user interface 3522. User interface 3522 may include a keypad, microphone, speaker, and / or display. User interface 3522 may include any element or component that conveys information to and / or receives input from a user of wireless device 3502.

  Various components of the wireless device 3502 may be coupled together by a bus system 3526. Bus system 3526 may include, for example, a data bus, as well as a data bus, a power bus, a control signal bus, and a status signal bus. Those skilled in the art will appreciate that the components of the wireless device 3502 can be coupled together using any other mechanism or can accept or provide input to each other.

  Although several separate components are shown in FIG. 35, one or more of these components can be combined or implemented in common. For example, the processor 3504 can be used not only to perform the functions described above with respect to the processor 3504, but also to perform the functions described above in connection with the signal detector 3518 and / or the DSP 3520. In addition, each of the components shown in FIG. 35 may be implemented using a plurality of separate elements. Further, processor 3504 can be used to implement any of the components, modules, circuits, etc. described below, or each can be implemented using a plurality of separate elements. As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” means calculating, calculating, processing, deriving, exploring, searching (eg searching within a table, database, or another data structure) ), Confirmation, etc. Also, “determining” can include receiving (eg, receiving information), accessing (eg, accessing data in a memory) and the like. Also, “determining” can include resolving, selecting, selecting, establishing and the like. Further, “channel width” as used herein may encompass bandwidth in certain aspects, or may be referred to as bandwidth.

  As used herein, a phrase referring to “at least one of a list of items” refers to any combination of those items, including individual members. By way of example, “at least one of a, b, or c” is intended to cover a, b, c, a-b, a-c, bc, and a-b-c. ing.

  The various operations of the methods described above may be performed by any suitable means capable of performing those operations, such as various hardware and / or software components, circuits, and / or modules. In general, any operations shown in the drawings may be performed by corresponding functional means capable of performing those operations.

  The various exemplary logic blocks, modules, and circuits described in connection with this disclosure are general purpose processors, digital signal processors (DSPs), application specific applications designed to perform the functions described herein. Directed integrated circuit (ASIC), field programmable gate array signal (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller or state machine. A processor may also be implemented as a combination of computing devices, eg, a combination of DSP and microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. obtain.

  In one or more aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer readable media can be RAM, ROM, EEPROM®, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage device, or instructions or data structures. Any other medium that can be used to carry or store the desired program code in form and be accessed by a computer can be provided. Also, any connection is properly termed a computer-readable medium. For example, the software uses a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology such as infrared, radio, microwave, website, server, or other remote source When transmitting from a coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, microwave are included in the definition of the medium. As used herein, a disk and a disc are a compact disc (CD), a laser disc (registered trademark) (disc), an optical disc (disc), a digital versatile disc (DVD). ), Floppy disk and Blu-ray disk, the disk normally plays data magnetically, while the disk stores data. Reproduce optically with a laser. Thus, in some aspects computer readable media may include non-transitory computer readable media (eg, tangible media). Further, in some aspects computer readable medium may include transitory computer readable medium (eg, a signal). Combinations of the above should also be included within the scope of computer-readable media.

  The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and / or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific step or order of actions is specified, the order and / or use of specific steps and / or actions may be modified without departing from the scope of the claims.

  The described functionality may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on a computer-readable medium as one or more instructions. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer readable media can be RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage device, or any desired form in the form of instructions or data structures. Any other medium that can be used to carry or store the program code and be accessed by a computer can be provided. As used herein, a disk and a disk are a compact disk (CD), a laser disk (disc), an optical disk (disc), a digital versatile disc (DVD), and a floppy disk. Disk, and Blu-ray® disc, which typically reproduces data magnetically, while the disc optically reproduces data with a laser Reproduce.

  Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such computer program products can store (and / or encode) instructions that can be executed by one or more processors to perform the operations described herein. A computer-readable medium may be provided. In certain aspects, the computer program product may include packaging material.

  Software or instructions may also be transmitted over a transmission medium. For example, software from a website, server, or other remote source using coaxial technology, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, wireless, and microwave When transmitted, their coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of transmission media.

  Further, modules and / or other suitable means for performing the methods and techniques described herein may be downloaded and / or otherwise obtained by user terminals and / or base stations, if applicable. It should be understood that this can be done. For example, such a device can be coupled to a server to facilitate the communication of means for performing the methods described herein. Alternatively, the various methods described herein may be provided via storage means (e.g., physical storage media such as RAM, ROM, compact disk (CD) or floppy disk), the storage means being a device. When coupled to or provided to, user terminals and / or base stations may be enabled to obtain their various methods. Moreover, any other suitable technique that provides the devices with the methods and techniques described herein may be utilized.

  It is to be understood that the claims are not limited to the detailed configuration and components illustrated above. Various modifications, changes and variations may be made to the arrangement, operation, and details of the method and apparatus described above without departing from the scope of the claims.

  While the above description is directed to aspects of the present disclosure, other and further aspects of the present disclosure may be devised without departing from the basic scope of the present disclosure. As determined by the following claims.

While the above description is directed to aspects of the present disclosure, other and further aspects of the present disclosure may be devised without departing from the basic scope of the present disclosure. As determined by the following claims.
The invention described in the scope of claims at the beginning of the application will be appended.
[C1]
A method for receiving transmissions from two or more wireless communication devices, comprising:
Receiving a first preamble transmitted by a first wireless device;
Simultaneously receiving a second preamble transmitted by a second wireless device;
Receiving a first portion of the transmission in a first section of bandwidth, wherein the first portion transmitted by the first wireless device includes a first data section;
Receiving a second portion of the transmission simultaneously in a second section of the bandwidth, wherein the second section of the bandwidth does not overlap the first section of the bandwidth; The second portion is transmitted by the second wireless device, the second portion including a second data section;
A method comprising:
[C2]
The first preamble comprises a first section transmitted using a first format interpretable by a wireless device having a first capability set and is interpretable by a wireless device having a second capability set A second section transmitted using the second format, wherein the second preamble uses the first format interpretable by a wireless device having the first capability set. The method of C1, comprising a transmitted third section and further comprising a transmitted fourth section using the second format interpretable by a wireless device having the second capability set. .
[C3]
The first section of the first preamble and the third section of the second preamble are each a first type of training field used for automatic gain control and an accurate frequency offset estimate. The method of C2, comprising: a second type of training field used for time synchronization and channel estimation; and a signal field.
[C4]
The method of C2, wherein the second section of the first preamble and the fourth section of the second preamble each include one or more training fields of the second type.
[C5]
The method of C4, wherein the amount of the one or more training fields of the second type from a particular device is based on the amount of spatial streams assigned to that particular wireless device.
[C6]
The method of C4, wherein the amount of the one or more training fields of the second type is based on the amount of spatial streams assigned to the wireless device to which the most spatial streams are assigned.
[C7]
The first section of the first preamble comprises a first training field of the first type, and the second section of the first preamble is the first type of the first type. The method of C1, comprising a second training field of the first type that includes a cyclic shift larger than the training field.
[C8]
The first preamble includes the first type of training field followed by one or more training fields of the second type followed by a signal field, and the second preamble is The first type of training field, followed by one or more training fields of the second type, followed by a signal field, and immediately following data, the second preamble The method of C1, wherein the number of second type training fields in is the same as the number of second type training fields in the first preamble.
[C9]
The first preamble includes the first type of training field, followed by one or more training fields of the second type, followed by a signal field, and immediately following data. The method according to C1 above.
[C10]
The first preamble includes one or more training fields of the second type, the second preamble includes one or more training fields of the second type, and the first The one or more training fields of the second type in the preamble are the first type of the second type in the second preamble in terms of time, frequency or via code. The method of C1, wherein the method is orthogonal to one or more training fields.
[C11]
The first preamble includes one or more training fields of the second type, and the transmission includes data sections sent over several spatial streams and several tones, The one or more training fields of two types transmit known symbols over frequency tones where each of the spatial streams spans both the first section and the second section of the bandwidth The method according to C1, wherein the method is sent as follows.
[C12]
The first preamble and the second preamble are each a signal field, followed by the first type of training field, followed by the second type of one or more training fields; The method of C1, comprising a subsequent signal field.
[C13]
The first preamble and the second preamble are each a first type of training field, followed by one or more training fields of the second type, followed by a signal field; The method of C1, comprising the first part and the second part of the transmission immediately following.
[C14]
The first preamble comprises symbols sent only within the first section of the bandwidth, and the second preamble comprises symbols sent only within the second section of the bandwidth; The method according to C1 above.
[C15]
The method of C14, wherein the first section of the bandwidth and the second section of the bandwidth each comprise non-overlapping tone sets.
[C16]
An apparatus for wireless communication comprising a receiver configured to receive a transmission over bandwidth, wherein receiving the transmission comprises
Receiving a first preamble transmitted by a first wireless device;
Simultaneously receiving a second preamble transmitted by a second wireless device;
Receiving a first portion of the transmission in a first section of bandwidth, wherein the first portion is transmitted by the first wireless device and includes a first data section;
Receiving a second portion of the transmission simultaneously in a second section of the bandwidth, wherein the second section of the bandwidth does not overlap with the first section of the bandwidth; A second portion is transmitted by the second wireless device, and the second portion includes a second data section.
apparatus.
[C17]
The first preamble comprises a first section transmitted using a first format interpretable by a wireless device having a first capability set and is interpretable by a wireless device having a second capability set A second section transmitted using the second format, wherein the second preamble uses the first format interpretable by a wireless device having the first capability set. The apparatus of C16, further comprising a transmitted third section and further comprising a transmitted fourth section using the second format interpretable by a wireless device having the second capability set. .
[C18]
The first section of the first preamble and the third section of the second preamble are each a first type of training field used for automatic gain control and an accurate frequency offset estimate. The apparatus of C17, comprising: a second type of training field used for time synchronization and channel estimation; and a signal field.
[C19]
The apparatus of C16, wherein the second section of the first preamble and the fourth section of the second preamble each include one or more training fields of the second type.
[C20]
A device for wireless communication,
Means for receiving a first preamble transmitted by a first wireless device;
Means for simultaneously receiving a second preamble transmitted by a second wireless device;
Means for receiving the first portion of the transmission at a first section of bandwidth, wherein the first portion transmitted by the first wireless device includes a first data section; ,
Means for simultaneously receiving a second portion of the transmission in a second section of the bandwidth, wherein the second section of the bandwidth overlaps with the first section of the bandwidth Without the second portion being transmitted by the second wireless device, the second portion including a second data section;
An apparatus comprising:

Claims (20)

A method for receiving transmissions from two or more wireless communication devices, comprising:
Receiving a first preamble transmitted by a first wireless device;
Simultaneously receiving a second preamble transmitted by a second wireless device;
Receiving a first portion of the transmission in a first section of bandwidth, wherein the first portion transmitted by the first wireless device includes a first data section;
Receiving a second portion of the transmission simultaneously in a second section of the bandwidth, wherein the second section of the bandwidth does not overlap the first section of the bandwidth; The second portion is transmitted by the second wireless device, the second portion including a second data section;
A method comprising:   The first preamble comprises a first section transmitted using a first format interpretable by a wireless device having a first capability set and is interpretable by a wireless device having a second capability set A second section transmitted using the second format, wherein the second preamble uses the first format interpretable by a wireless device having the first capability set. The method of claim 1, further comprising a transmitted third section, further comprising a fourth section transmitted using the second format interpretable by a wireless device having the second capability set. Method.   The first section of the first preamble and the third section of the second preamble are each a first type of training field used for automatic gain control and an accurate frequency offset estimate. The method of claim 2, comprising: a second type of training field used for time synchronization and channel estimation; and a signal field.   The method of claim 2, wherein the second section of the first preamble and the fourth section of the second preamble each include one or more training fields of the second type. .   The method of claim 4, wherein the amount of the one or more training fields of the second type from a particular device is based on the amount of spatial streams assigned to that particular wireless device.   The method of claim 4, wherein the amount of the one or more training fields of the second type is based on the amount of spatial streams assigned to the wireless device to which the most spatial streams are assigned.   The first section of the first preamble comprises a first training field of the first type, and the second section of the first preamble is the first type of the first type. The method of claim 1, comprising a second training field of the first type that includes a cyclic shift larger than a training field.   The first preamble includes the first type of training field followed by one or more training fields of the second type followed by a signal field, and the second preamble is The first type of training field, followed by one or more training fields of the second type, followed by a signal field, and immediately following data, the second preamble The method of claim 1, wherein the number of training fields of the second type in the same is the same as the number of training fields of the second type in the first preamble.   The first preamble includes the first type of training field, followed by one or more training fields of the second type, followed by a signal field, and immediately following data. The method of claim 1.   The first preamble includes one or more training fields of the second type, the second preamble includes one or more training fields of the second type, and the first The one or more training fields of the second type in the preamble are the first type of the second type in the second preamble in terms of time, frequency or via code. The method of claim 1, wherein the method is orthogonal to one or more training fields.   The first preamble includes one or more training fields of the second type, and the transmission includes data sections sent over several spatial streams and several tones, The one or more training fields of two types transmit known symbols over frequency tones where each of the spatial streams spans both the first section and the second section of the bandwidth The method of claim 1, wherein   The first preamble and the second preamble are each a signal field, followed by the first type of training field, followed by the second type of one or more training fields; The method of claim 1, further comprising another signal field subsequent thereto.   The first preamble and the second preamble are each a first type of training field, followed by one or more training fields of the second type, followed by a signal field; The method of claim 1, comprising the first portion and the second portion of the transmission immediately following.   The first preamble comprises symbols sent only within the first section of the bandwidth, and the second preamble comprises symbols sent only within the second section of the bandwidth; The method of claim 1.   The method of claim 14, wherein the first section of the bandwidth and the second section of the bandwidth each comprise a non-overlapping tone set. An apparatus for wireless communication comprising a receiver configured to receive a transmission over bandwidth, wherein receiving the transmission comprises
Receiving a first preamble transmitted by a first wireless device;
Simultaneously receiving a second preamble transmitted by a second wireless device;
Receiving a first portion of the transmission in a first section of bandwidth, wherein the first portion is transmitted by the first wireless device and includes a first data section;
Receiving a second portion of the transmission simultaneously in a second section of the bandwidth, wherein the second section of the bandwidth does not overlap with the first section of the bandwidth; A second portion is transmitted by the second wireless device, and the second portion includes a second data section.   The first preamble comprises a first section transmitted using a first format interpretable by a wireless device having a first capability set and is interpretable by a wireless device having a second capability set A second section transmitted using the second format, wherein the second preamble uses the first format interpretable by a wireless device having the first capability set. 17. The transmitted third section of claim 16, further comprising a fourth section transmitted using the second format interpretable by a wireless device having the second capability set. apparatus.   The first section of the first preamble and the third section of the second preamble are each a first type of training field used for automatic gain control and an accurate frequency offset estimate. 18. The apparatus of claim 17, comprising a second type of training field used for time synchronization and channel estimation, and a signal field.   17. The apparatus of claim 16, wherein the second section of the first preamble and the fourth section of the second preamble each include one or more training fields of the second type. A device for wireless communication,
Means for receiving a first preamble transmitted by a first wireless device;
Means for simultaneously receiving a second preamble transmitted by a second wireless device;
Means for receiving the first portion of the transmission at a first section of bandwidth, wherein the first portion transmitted by the first wireless device includes a first data section; ,
Means for simultaneously receiving a second portion of the transmission in a second section of the bandwidth, wherein the second section of the bandwidth overlaps with the first section of the bandwidth Without the second portion being transmitted by the second wireless device, the second portion including a second data section;
An apparatus comprising:

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